Through the years of participating on this forum I have yet seen any strong proponents of using straps and comealongs to pull joinery together and then boring holes. I would not be concerned with drying of timber changing peg alignment. An exception would be naturally curved timber which should be dried before joinery, like curved brace stock with long tenons.
Again, the sure fire way of ensuring proper peg fitting would be test fit and pricked peg locations with an 1/8 - 3/16 inch draw bore.