You can do it either way. I just put a MannMade trem on a Clapton Strat. The front edge of the trem is angled on the bottom. Clapton's have blocked tr9ems as it is, so I didn't use the 2.5mm rule since that is really about getting it to float. I went as low as I could with the trem screws until the rear of the trem started to lift off the body because of the angled edge on the front. I'm not sure if I typed this very clearly, but if you look at the trem, I think you'll get it.
Bottom line, if you go too far with the trem screws, the back edge of the trem will lift, just like if you were depressing the whammy bar. Go to that point, and back off.