Congrats! I bought my 39 about 6 months after I got my 38. The 38 is my cold weather off duty carry and the 39 is summer carry. Even though it's a hair thicker in the slide, it will fit in most 26/27 holsters. Leather holsters are a piece of cake. Put the pistol in, struggle a little to snap it shut (I like thumb breaks) and let it sit in the holster for a week or so. After that all is good to go.
My favorite holster for my 39 at this point is my Comp-Tac paddle. Much better build quality than Fobus - it's a one piece holster unlike the Folbus pop rivet special. It also rides higher than the Fobus.
No problem finding GAP ammo either. I stocked up on SD carry ammo (Speer GDHP 200gr) and load my own for practice (Berry's bullets 185gr RNHB).
Since I bought my GAPs my 19 has been guarding my safe.
"Among the many misdeeds of British rule in India, history will look upon the Act depriving a whole nation of arms as the blackest." - Mohandas Gandhi, an Autobiography, page 446.