As you might have seen from the last boost, there's an unofficial reminder bot by @atasfun available on here at:

➡️ @remindme

It can remind you about a post in a few minutes, hours, days, weeks, months or years later.

To use it, mention the bot and then the time you want to be reminded (for example "1 week").

If you want the reminder to be private, include the phrase "dm" as well. If you do that, the bot will send you your reminder by a private mentions post.

(Thanks to @j3j5 for info!)