If you don't own the Traditional Bowyer's Bible series I thru IV, I think you'd find a lot of good info here Re: subj.
Not so sure you have to follow a template for the fades but being your first bow I suppose this could help. I would suggest developing your own feel for this sort of thing thru experience and based on the the above writings. Tim Baker in particular, has outstanding information re: pyramid bows. Also reference Chapter 4 "The Mass Principle" by Steve Gardner in TBB IV.
It is an art as much as a science, so don't be afraid to make mistakes...you will be building many bows if this is your thing, so have at'er!
For me it's all about the learning (the process) the desired product will only come with experience and knowledge.
Best of Luck! As Tim Baker says, "make some shavings and break some wood" (or something to that affect)
Kris