I can picture what you're doing in my head so I'll give you some of my thoughts without actually seeing it.
The main thing I tell people when trying to initiate the 2nd pull too soon is "BE PATIENT." That 1st pull may seem like it's going to take forever (especially with the heavier weight) but let it.
Also, try thinking about keeping your feet flat longer. This may help you keep from "chasing" the bar and jumping forward.
Halting Snatch/Clean DLs - stay over the bar throughout the movement.
Snatch/Clean from high blocks - start with your weight distributed toward the back of the foot and focus on pushing the bar all the way into your body before initiating the 2nd pull.