I know you’ll be starting this in 2 days but an emergency host maintenance a couple of hours ago broke an app of mine.
This app has a single machine which is in charge of processing queues, triggering jobs, etc.
Some things started failing and it was because this app now had 3 machines running and triggering jobs thrice.
Please take this into account for the migration. If an app has a single machine you should not be creating new machines.