I don’t think your hip rotation is late. Rather than starting your hip rotation earlier, I would suggest trying to delay shoulder rotation longer. And that starts with the glove arm. Since you drop your throwing arm down behind your, your glove arm’s “opposite & equal” position should be up in front. Failure to get it high enough will shorten its path and make it too quick. I think this is what the person talking to you in the video was getting at.
The other thing I would check is your time into front foot plant. Going from the stretch, have someone put a stopwatch on you and time you from first movement to front foot plant. Shoot for .90 - .95 seconds which should be possible even with a knee lift (in other words, you don’t need to use a slide step).