If your flyer 1st shot only happens on the #1 shot from a cold barrel regardless of whether the 1st shot is thru a clean barrel and the rest are through the fouled barrel...then I' d advise you to add a small chunk of material near the end of your fore-stock to put slight upward pressure on the barrel. A piece of credit card might be perfect if your barrel is free-floated...or could be too much, ..you' ll have to experiment. If your barrel is NOT free- floated then try adding something thinner....(small bit of folded aluminum foil). If your barrel is NOT free-floated and the upward pressure doesn' t work...then try free-floating. Just some thoughts to try. Either way, make sure your first shot is thru a clean and DRY barrel.
good luck