Since the flippers make it easier to propel yourself through the water, it isn’t going to help out in the long run. The only thing they might do is let you see how it feels to be in the right position (since it will be easier to get in the right position with flippers on). My understanding is that one doesn’t use their legs to propel themselves through the water so much as help stay in a more horizontal (i.e. less drag through the water) position. You should focus on keeping your legs straight (not locked, but not much bend at the knee).

Have someone who knows their stuff have a look at your stroke, and give you advice. I made the biggest leap in time after some good advice.

John