Promoting a Webinar on Social Media: A Reminder Schedule You Can Hand to an AI Agent

TL;DR: A webinar needs repeated exposure, not one announcement. Plan four posts (announce, week-before, day-before, hour-before) plus a replay post, give every post its own tracked link, and write the facts once so an AI agent can reshape them for each platform. Keep Reddit and replies manual.

You set the date, booked the guest, and built the registration page. Then you posted one announcement on LinkedIn, got eleven likes, and the page sat at four signups until the week of the event.

That’s the usual shape of webinar promotion: the event is easy to plan and the reminders are tedious. Most “how to promote a webinar” guides say the same thing, that a single post won’t do it because most people don’t register the first time they see it. A Metricool guide to webinar promotion frames social posts as a countdown campaign, and Zoho’s webinar guide lists platform by platform where to put them. What they leave out is the practical part: who writes and schedules a dozen small variations of the same four facts.

This guide gives you a schedule, a template for each post, and a way to hand the repetitive part to an agent.

The four-post reminder schedule

Vendor guides disagree on exact numbers. Some say start two to three weeks out, others four to five. Treat all of them as starting points and adjust to how long your own audience takes to decide. The structure below works for a typical 45-minute free webinar.

Post 4 is mostly for people who already signed up. Post 5 is where you earn a second audience, because a lot of registrants register in order to get the recording.

What every post needs

Each post should work if it’s the only one someone sees. That means the same five items every time:

1. What the webinar covers, in one line that isn’t just the title.
2. Date and time with an explicit timezone. “Thursday 3pm” is useless across a global audience, so use UTC or give two or three conversions.
3. Who is speaking and why they’re worth hearing.
4. One link, to a registration page that needs no account.
5. A tag for the guest or co-host, so their audience sees it too.

Tag guests only if they’ve agreed. A guest who reshares post 2 is worth more than any hashtag.

Give every post its own link

If every post points to the same URL, you’ll know the webinar got 140 signups and nothing about why. Add campaign parameters so each platform and each phase can be separated in your analytics. Google documents the standard utm_source, utm_medium and utm_campaign parameters in its campaign URL guidance.

A simple convention:

?utm_source=linkedin&utm_medium=social&utm_campaign=webinar-oct&utm_content=week-before

Change source per platform and content per post. Then after the event you can see that, say, the “tomorrow” post on X brought more registrations than the announce post on LinkedIn. That tells you what to do differently next time, which is the point of the weekly review workflow.

Per-platform adjustments

The facts stay the same. The shape changes.

• LinkedIn: A few sentences, written like you’d explain it to a colleague. Lead with the problem the webinar solves. Metricool suggests an event page on LinkedIn or Facebook, which collects RSVPs and sends reminders, so use it if your audience is professional.
• X: Short, one image, the date in the first line. Pin the announce post to your profile until the event. Reminders can be near-identical, since few followers see more than one.
• Bluesky and Mastodon: Same short text, plus alt text on the image. On Mastodon, hashtags are how most strangers find you, so add two or three in CamelCase such as #DevRel or #OpenSource. If your audience cares about it, mention which tool the webinar uses.
• Dev.to, Hashnode or Medium: A short post that explains the topic of the webinar, with the signup link at the end, often reaches people more than a plain “register now”. It also keeps working after the event. See how to automate Dev.to posts.
• Reddit: Each subreddit has its own self-promotion rules. Some ban webinar links outright. Read the sidebar, and if it’s allowed, post something useful (an outline of what you’ll cover, a question you’ll answer live) rather than an advert. Do this one by hand.

Don’t schedule everything blindly

An automated schedule goes wrong in three predictable ways:

• The date changes and posts 2 to 4 still carry the old one.
• The guest cancels and “with Special Guest” goes out anyway.
• The “starting soon” post publishes after the event started because of a timezone mix-up.

Whatever tool you use, keep the schedule in one file and re-read it the day before. If the event moves, delete the queue and rebuild it, don’t patch it post by post.

Handing the reshaping to an AI agent

Four posts across four platforms is sixteen drafts. The drafts are mechanical, but the decisions aren’t, so split the job:

You write a webinar.md: title, one-line description, date in UTC, speaker names and handles, the base registration URL, the single takeaway for post 2, and the platforms you want. The agent turns this into per-platform drafts with the right UTM parameters, and you approve them.

With PublishPort, you log in to your own accounts once in the desktop client. Your AI agent connects through the relay, calls list_capabilities to see which platforms you have connected, reads each tool’s -h output, and posts from your own logged-in sessions. Posts that need to go at a specific time can be queued or sent live at that moment, and you can ask the agent to dry-run first. See the pricing page for which plans cover what. If you haven’t had an agent post for you before, run a throwaway test post first.

For the general pattern of writing once and posting everywhere, see repurposing one post across platforms. The same three-wave idea applied to a talk at someone else’s event is in promoting a conference talk.

Limits

• The desktop client must be running and logged in when a post is due. If your machine is asleep at 14:00, post 4 doesn’t go out.
• Platforms change their composers and rate limits. Expect an occasional failure and check the result rather than assuming success.
• The agent can’t tell you whether the time suits your audience. Look at when your past posts did well.
• Replies to questions about the webinar should come from you.

Checklist

• webinar.md with UTC time, speaker handles, base link
• One UTM-tagged link per platform and per post
• Post 2 has one concrete takeaway
• Guest has agreed to be tagged
• Reddit post written by hand and checked against subreddit rules
• Queue re-read the day before
• Replay post drafted before the event

FAQ

How many social posts should I make to promote a webinar?

At least three is the common minimum in vendor guides (early, one week before, day of). Four plus a replay post is a reasonable default. More than that on the same account in the final week starts to look repetitive, unless you vary the angle.

How far in advance should I start promoting a webinar?

Guides range from two to five weeks. Start when your registration page is ready and your guest is confirmed. A longer runway helps for paid or niche topics, where people plan their calendars ahead.

Which platform is best for promoting a webinar?

It depends on where your audience already is. For professional topics, LinkedIn plus an email list usually leads. For developer topics, X, Bluesky, Mastodon and Dev.to are more likely. Use your own past link clicks to decide, not a general ranking.

Should I post webinar links on Reddit?

Only if the subreddit allows it. Many don’t, or limit self-promotion to a small share of your activity. A useful post that mentions the webinar is safer than an announcement.

Can an AI agent promote my webinar for me?

It can write the drafts and queue or send them from your connected accounts. You still decide the angle, check dates and handle replies.

What should I post after the webinar?

A replay post with the recording link and one highlight with a timestamp, a few days later one lesson from the Q&A, and a thank-you to the guest.