I want a 21 second 50 fly SCY

I've had some lofty goals for my 50 back in the past.  I got back down to a mid 22 second 50 Backstroke in 2012.  It's time to push the limits in my butterfly.  I want to be impressed when I look up at that clock.  An impressive swim for me would be a 21.9 in the 50 Fly.  I've been a 22.25 just a few years ago.  I've never trained butterfly this much.  I've barely scratched the surface of my butterfly abilities.  I could be right or wrong about that assessment.  I'm admitting I haven't trained to maximize butterfly and I need help analyzing my stroke to ensure I'm not wasting energy or missing my catch.

I'm gonna swim a 21 second butterfly race, and you'll see me smile at the clock.

After that, I'm gonna demolish my 2012 50 Fly long course time of 24.59