I am on test prop 150EOD and 100ED NPP right now.And I can tell u I am on a week 8 and my gains stopped right now I'm planning to do 4 more weeks and then pct.
So I'm doubt that 15-20weeks would be beneficial.
For the bridge u might want to look in sarms s-4 and bridge from needto.
Also add clomid to nolva PCT 100/100/50/50 and add 1000iu week HCG starting from week 3 and run it thru the cycle that should hold on to most of your gains.