One common hitting cue I heard from coaches when I played was "get your foot down" and for me that created a two part swing where I stopped all my momentum and rhythm. I say this because I see so many kids being taught this by coaches these days.
What worked for me was to think "be on time" whether that's starting everything (leg kick, leg lift, toe tap etc.) earlier or later (based off the pitcher). Here's some swings from today's game of @abreg_1 , @josealtuve27 & @bharper3407 and as you can see as soon as their foot hits the dirt the hips begin to clear. They're NOT stopping and starting their momentum.