Ckeck your recoil spring assembly, if it has an 04 on the end that attaches to the barrel then any good quality 115 gr ammo should be fine. If not, break it in with 124 gr quality ammo for the first 300 rounds or so. Also, if you get a chance, get some Winchester NATO 124 gr FMJ ammo. There's a lot of it floating around lately at excellent prices.
Enjoy your first handgun, enjoy your first GLOCK, you couldn't have picked a better pistol than the G19 Gen4 to start with. One more thing... Read The Manual.