Post scheduling means you write posts now, and they are automatically posted later at times and dates of your choosing.
This is very useful for accounts that need posts to go out at particular times of day, for example to reach people reading their feeds in particular time zones, or to accompany scheduled live events such as streams or radio shows.
Scheduling through third party apps
If you are using certain third party apps such as Tusky and Fedilab you will find scheduling options built into their posting interfaces. Fedilab also runs a website interface at FediPlan ⧉ which lets you access the scheduling feature even without the app.
If you’re techy and want to self-host a scheduling app, there’s a new free open source third party web app called Mastodon Scheduler ⧉.
Professional post scheduling services
There are now commercial companies offering advanced post scheduling services that include compatibility with Mastodon and other social networks. The two most prominent at the moment are Publer ⧉ and Buffer ⧉.
Why doesn’t Mastodon have a built-in scheduler?
This is the weird part… Mastodon does actually have a fully functional built-in scheduler buried deep in its code! However, for some unexplained reason, the official web interface and official apps don’t yet give you any way to access it. This means you can only use Mastodon’s post scheduling system through third party apps and services via the Mastodon API.
If you’re comfortable using Github, you can vote for an official Mastodon scheduling interface to be added by giving a thumbs up at this issue ⧉.