Should be able to start with the data published on-line by Hodgdon for Titegroup and the Hornady 90 JHP. May have to adjust COL a little if the XTP and JHP are a little different shape.
3.0 gr Titegroup, WW 95 gr FMJ, chronographed at 864 fps out of my Sig P232.
Shot about as well as anything else. TG is an OK powder in the .380. There are quite a few that will work well, in the fast to medium burn rate category.