How to do variable threads for a bottle & cap? (All files provided)

I'm trying to do a 2-3 revolution thread on both the bottle & cap.
Pitch is .2in on 1st and or 2nd revolution & .375 on last revolution.
Pitch spec's can be tweaked a little.
Function I'm needing is for the 1st twist of the cap to loosen right away & the last twists to be more secure. I've tried using a helix sweep with close results, but I guess my skills aren't there yet. Thanks in advance...this will finish my project & I've been stuck on this for about a week.

Scott Hartley
310-402-1608