I press as I go and don't worry about twisted seams. I can't tell they're twisted after the quilting is done. I don't press again after the top is done, but I might if I were sending the top out to be quilted. If the back is wrinkled I spritz it with water after it is loaded on the longarm and stretch it between the rails. I let each section dry before rolling on to the next section. That seems to take care of wrinkles much more effectively and efficiently than pressing with an iron.