Yeah its not an exact science for sure, if I was going to do it again I would figure out exactly how many points I need for the room I want and divide by 3, but the problem I have found is that a)I was adding on slowly and could only afford so many points at a time I actually started with only 25 points! and b)as in the case of WLV my needs changed, I have exactly enough points for 7 nights in a 1 bedroom for January when I go, but now I want more then 7 nights.
So to give you an idea here is how my last few years have worked out:
January 2013, 7 nights WLV 1 bedroom used exact points (stayed 2 extra nights at Wilderness Lodge in a inn room)
January 2014, 2 nights BCV, 9 nights BLT standard view studio, booked BLT using BLT points at 11 months, booked BCV borrowing from the next year's OKW points (because I figured out exactly how many I would need to next year for OKW, and used the rest this year)
January 2015, OKW, using OKW points and the 16 points left over from BLT the previous year, booked 10 nights at OKW (was changed later to 5 nights OKW studio, 5 nights BWV standard view studio)
Jan 2016, Polynesian Standard view studio 8 nights, followed by 4 nights in a 1 bedroom at WLV (since this would have normally been WLV rotation year, I had to use some of those points)
So basically I use all/or as many as I can at 11 months, and use what ever is left, or whatever I know I will have left over for the next year at 7 months. I can definitely see how this would be confusing, but it also means I get to stay at BLT, Poly and WLV for Marathon weekend every year. Otherwise I would be stuck at the same place all the time, and as you can tell from my split stays I like variety. BTW I have never lost a single point.
Jennifer