How to know when "transition is complete"?

I've seen several comments about waiting "until the transition is complete" before making any user or sever changes.  OK, but when is that?  How am I supposed to know when?  Or better is there some kind of status page that show where I am in the transition/user changes?

I've gotten three emails from Cox so far:

1. The first on February 3rd. Your Cox.net email is moving soon to Yahoo Mail.
2. A second one on March 22.  Your Cox.net email will soon move to Yahoo Mail
3. A third March 23:  Cox Important Update!!! ...

When is when?  And maybe an list of ordered steps of what to do then?