Normal stretch routine with teammates. If you are not familiar with Jaeger's band routine, check into that. A light version of the band routine works for many P's prior to a start. When doing warm up tosses, get some light flat ground to get rhythm and feel for all grips. Time your actual pen warm up based on game start time and home or visitor. I think 10-15 minutes before you will take the game mound is good. Be sure to work from wind and stretch and get reps on all pitches. Be very specific with target location. Some have a specific sequence of pitch types and locations as part of their routine (not so much with 14 y.o.'s maybe). When getting hot, use game velo and rhythm. Ideally, your catcher will be able to work with you so you two can start syncing up before game. Don't get your bullpen pitch count up so much that you will tire early in the game.