I’ve made an app that makes it possible to schedule a post in Lemmy at an arbitrary time. It’s available at https://schedule.lemmings.world and can be used by people from any instance.
Let me know what you think!
P.S. This post is made using the app!
Edit: And it’s open source!
The way I run it it’s entirely serverless and costs you close to nothing.
All in all the app can be hosted for much less than $1/month like that. If you host it in a standard docker container or something, it probably won’t take much resources either, my guess would be less than 256 MB RAM (probably less than 100 MB) is needed and whatever your backend for scheduling takes (Redis would probably be the most straightforward choice).