Things can change on a dime, but I know some letters saying "expect a class no earlier than next year..." have gone out.
Great to get the invite--go get the job! But plan on some pool time--maybe just a couple months but the pragmatic guy will plan for 6-12 just in case.
Had a friend who was expecting to be in the pool for a year or more...ended up being about 7 months after his type date. Lots of variables right now...