As and instructor at our field I have a little experience with people in your position. First off, an instructors job isn't finished when the pilot makes their solo flight. I am still out there with my student to help them when they get into a situation that they don't know how to handle. And most times when a student moves up to their second plane, I will help them in assembling it correctly, trim flight it for them, and then put them on the buddy box for their first flight on that new plane. But that's just how I like to teach people. I don't like to see people get frustrated with the hobby and leave because they tried to move to quickly to more advanced planes.

As for the question at hand. How long should you spent on the trainer?? My advice to my students is fly it till the covering falls off. I advise them the spend whole days of doing nothing but touch and gos. Then do nothing but go up, cut the throttle, and dead stick it. etc....... IMHO it makes for a pilot that is fully prepared for anything in this hobby.

and just because you have your AT-6 doesn't mean you can't still fly your trainer till you are ready to move up. It's always better to wait till you are ready, then bring that warbird home in a garbage bag.

Just my 2-1/2 cents worth