As discussed on the chat, I would suggest using the same list as the release one (just indicated next to the name who is also OK to do xwiki.org upgrades) so that you don’t end up doing both a release and an xwiki.org upgrade very close.
We also need to anticipate that some onboarding will be required for new volunteers. But this is also a good opportunity to improve the upgrade documentation.
Closing this as agreed with 4 +1. I will create the events in the shared calendar, and I’ll check with committers for reusing the list of release managers for the upgrades.