I think you mean year and a half, and time is irrelevant, it is all about the individual. It all depends on your skiing/athletic ability combined with the size of your balls.
time doesnt matter...if u think u can do a flip then just commit and keep trying till you land it..at ur level learning tricks is a pretty simple process... 1. visualize 2. commit 3. repeat
if you are going to start fliping, start with backflips. they are much easier and feel more natural. a friend of mine told me that if you can ski well then you can phisically backflip. i think it mostly depends on your mindset though