I have had several opportunities to put together frames that wher cut over extended periods of time. Our church frame was cut in 1815, but some of the pieces used to put it back up were milled six months before we raised it. It was frustrating at times, but it all went together.
Since wood shrinks in the cross grain direction, but not in the long grain direction, drying can cause joints to be loose or tight, depending on which is cut when. The problem with "mapping" shrinkage is it can add a lot of time to the joinery process, and it can easily lead you to the same problem you get when you start trimming table legs to get the wobble out. Eventually you have a table with no legs.
I would recommend cutting everything to the square rule standard you have chosen and leave it at that. We usually work to 1/2" under nominal. As far as predrilling pegs, we NEVER drill pegs until it's time to prep for the raising. The holes become oval shaped when the timber dries, and exposing that much more end grain only adds to shrinkage distortion and checking.
Enjoy your project and remember "It ain't furniture!" I think Jack Sobon first told me that, and I'm sure I had it coming.
Rudy
