How do I change the maintenance window for Heroku Postgres?

You can check to see if maintenance is required on databases using the CLI tools:

heroku pg:maintenance -a APP_NAME
Maintenance not required, window is Fridays 22:00 to Saturdays 02:00 UTC

Your maintenance window can be changed using:

heroku pg:maintenance:window postgres-slippery-100 "Sunday 06:00" -a APP_NAME

This will change your maintenance window to every Sunday morning, 06:00 UTC to 07:00 UTC.

If you want greater control over maintenance, you can manually run maintenance on your database using:

heroku pg:maintenance:run postgres-slippery-100 -a APP_NAME