Well, I'm left handed....
The Glock (or at least the Glock's I own) don't auto forward for me with enough consistency to depend on it....
I have put a little effort into staging my trigger finger...about at the joint closest to the rest of my hand atop the slide release (extended slide release) and when I insert the mag it sends the slide home. But I have inadvertently sent the slide home prematurely.
So for now I grasp the slide.
There are two ways to do this FAST!
One, rotate your palm from inward to outward after you've insert the mag you are in line to go straight up and overhand grasp and release the slide....
Or two, hand is inward, after insertion pinch the slide with the thumb and fore finger forward of the ejection port and send home. Here is a video of me doing a slide lock reload like this. I have never done one before with this particular pistol and hadn't shot a compact Glock in about 10 years. This was like rounds 2-7 ever fired with it. I do have an issue with the insertion of the mag though...
https://youtu.be/1R45Kf4z2ts?t=34s
As stated above, reaching underneath and hitting the slide release is an option too.