Though I wasn't in A-pool for very long, I don't know many folks who just went off and did TAD while they were there. While the wait was long for many, it wasn't necissarily a "we need you to start in 3 weeks, see ya" as much as it was a "expect 3 weeks but standby". If that has changed, then so be it, but A-pool always seemed to be flexing on a weekly basis. If you can convince them to let you go TAD for several weeks, then go for it, but I wouldn't count on it. If it doesn't work out for you there, you should have the opportunity to do it either before classing up for primary, or do what I did and go prior to classing for advanced (which can be a considerable wait for some folks).