All going well, I will be starting the upgrade to v2.5.0 for all Masto.host hosted instances in a couple of minutes.
This release will take longer than usual to upgrade, so I can't say how long it will take until your instance is updated. If I believe it will take a long time, I will post information about it.
The upgrade should cause less than a 1 minute backup.
You can read about what changes here: https://github.com/tootsuite/mastodon/releases/tag/v2.5.0
Pretty cool stuff coming :)