"Melt" isn't really what poly's do.
What you are really doing is spraying tac coats and they shouldn't be too thick.
You have the right time-frame between coats, but you should start with a thin coat, wait, thin coat, wait and thick coat. Let dry for about 36 hours and do it all over again.
With rattle-cans, you should wait until after your second go-around before starting to knock down high spots.
I would suggest starting with 1000 before round 3 and work your way finer between rounds.
5 rounds should do it for a thick application and then you should be near you final destination of 2000.
After that, buffing will be next.