Ok, then you’ll first want to get an understanding of when your hips currently start forward relative to your knee reaching the apex of the knee lift. (The apex of the knee lift is a good checkpoint by which to compare the start of hip movement.) Have someone watch you and let you know when you start forward. Once you know this, then you can start to make adjustments.
If your hips start forward right at the apex of the knee lift, then try to start them forward slightly before the knee reaches the apex (i.e. while it is still on its way up). Also try to get your hips going a bit faster in addition to sooner. Start off making a small adjustment. Practice that and then make another small adjustment. And so on and so on. Make sure you don’t sacrifice your knee lift. Instead swing the stride leg out front faster. This will definitely feel awkward at first and will take lots of reps for you to get comfortable with it. Give it a chance.
The following drills will help you practice this:
(1) Stand perpendicular to a chain link fence with glove side next to fence and throwing arm side foot about 8"-12" from the fence. Simply lift the knee and push the hips into the fence. This is a simply way to practice starting the hips sooner.
(2) Cross-over drill: Stand in the stretch position. Then cross the stride leg over in front of the pivot leg. Bend the knees a bit if necessary to get the stride foot heal to touch the ground. Simply go through your pitching motion from this position concentrating on getting the hips going. The crossed-over position helps emphasize the hips since it puts you in a position where the hips are already out front. This drill can be done on flat ground and from a mound.
(3) Narrow stance drill: Same as above but instead of crossing over the front leg, simply place the stride foot next to and touching the pivot foot.
(4) Normal stand drill: Same as above but using your normal starting stance.
Drills 2-4 above represent a progression from a position that over-exagerates things to your normal stance.
Make sure when getting the hips going that you don’t introduce a posture issue. The head and shoulders will stay slightly behind the front hip into release but there shouldn’t be a big lean back toward 2B.