I don’t anticipate upgrading in time will be a challenge for Stacking Pools, they won’t even need to sync from genesis. Otherwise, nothing about Stacking behavior has changed, so they won’t need to change UI/UX or anything.
The timeline for Stacking is covered in the release update, including a graphic. I’m really not sure how to make it more clear than that, but open to your ideas if you can provide specifics.