Woohoo! Welcome Little One! Way to go, Mama!!!!
As far as preferring one side, one thing that helps some is if you're doing the football hold on the side he prefers, then do the cradle hold on the side he's not accepting (or vice versa) so that his "approach" to the breast is the same. Could be a chiropractic issue or cranial sacral issue if it doesn't easily resolve (as in it causes him pain to turn his head to that side). Hope it's a non-issue by the time you read this post anyway!