That sounds almost identicle to my first trip to the range lol except the range owner didnt shoot with me. I went out by myself after some basic instruction on how not to shoot myself and how to work the gun properly
If im not mistaken the G17 is a 9mm. I shot with a .40 my first time, so Im a little bit worse off than you were. How far out were you shooting? My first time, I hit the target about 30-35 times out of 50 shots, from about 10 yards away. Most of my shots were in the bottom left like yours, with maybe 4 or 5 in the red.
Your problem is coming from a combination of anticipating recoil, and too little trigger finger. Im going to give you tips that should help you:
First-establish a proper grip if you havent already (I dont know if he told you the proper way to grip a handgun) but if you already know, then thats great.
Second-next time you go, use a little bit more trigger finger. Try and pull the trigger back with the pad between the tip of your finger, and your first joint.
Third-remember your grip should be 20% with your strong hand and 80% with your support hand. This means, squeeze tight with your strong hand, and EVEN tighter with your support hand.
Fourth-take is slow. First thing to work on is anticipating the recoil. Next time you go, get a target with a small bullseye, and take it out about 5 yards at first. Shoot three rounds at a time, slowly, working on accuracy. The gun should surprise you when it goes off. If you try and guess when the gun is going to go off, you will anticipate the recoil, and your shot will be low below the bullseye. Eventually, you will learn when the gun shoots, and you will subconciously realign the sights for the next shot. You just need practice. Its all "muscle memory"
After you work on accuracy, and you start getting within an inch of the small bullseye on the target at 5 yards, get a bigger target, and take it out to 5 yards at first, then when youre comfortable, take it out to 7 yards, then 10. 10 yards is a good distance to practice at. I was terrible at first, but ive went about 10 times, and now I shoot good. I can get it in the 7 ring or better every shot up to 10 yards, but after that, it starts to get innaccurate, and I cant even hit the target at 25 yards. I gotta work on my long distances.
EDIT: One more thing....I dont know if you shoot with one eye closed, but if you have been, make sure you were shooting with your non-dominant eye closed. If you dont know how to check it, let me know and Ill tell you how to see what eye dominant you are. I made the mistake of closing the wrong eye the first time I went, and it messed me all up. Thats why most of my shots were off the first time. I actually urge you to try and learn to shoot with both eyes open, but we'll take one thing at a time. I learned to shoot with both eyes open, and I havent even been shooting that long. Its so easy once you get used to it