I have moved a few accounts from one proxy to another and I've followed the next steps:
1. Stop all actions on the account for 2-3 days, let it rest offline
2. Log in with the new proxy (I've usually had to PV, depending on the proxy location, in some cases it didn't even ask me to PV, but in others it did, I would say 50% chance)
3. Let the account rest for another 2-3 days, logged in but not performing any actions
This has worked quite well for me, besides from a PV when logging in to the new proxy in some cases nothing else was needed. When the proxy location was the same as the previous one, I did not get PV's so definitely recommend to keep the same location. I tend to be a bit conservative, I'd rather wait a bit more time before doing actions on a new proxy than risking an account, but of course it's just my experience