[thejeff]

Almost right, I think.
Mages will research with the magic scale penalty (if one exists) of the province they are in, regardless of who's dominion is in that province.
They will only get the research bonus from the magic scale if the province has your dominion.
Since your scales won't take effect until after your dominion does, you can get the bonus for a short time.

It's generally not something to count on. Trying to exploit it is usually done with bad scales, low dominion and a blood sacrifice nation to keep your dominion alive. Heretics can also be used to avoid scale penalties.