Just so you know, hardened rubber seals will cause that also.
With hard rubber in the trans it takes awhile for the heat from the engine to warm up the rubber and let it flex enough to seal.
If it takes less than 30 seconds in neutral to be able to move fine.
If it takes 5 min, then it's the rubber seals.
I see all the time on here where people mention the converter drainback issue, but no one ever mentions that old hardened rubber does almost the exact same thing.
(warmup time before it'll move is the tell tale sign, as the converter will fill in a few seconds) but seals have to get warm from the engine coolant and that takes awhile on a cold startup.
Don't bother telling us it only has however many miles on it, because it doesn't matter.
The age of the rubber, and the clearances in the pump and bushings are what matter.
Not miles.