I think 50 points is just not enough. You should get twice as much, or more, if you can. I REALLY don't think you would ever REGRET having the additional points. But DO make sure they are the same resort and Use Year, so you can roll them into one account. 50 points each in two different accounts would just be frustrating. I kind of run into that because I have Animal Kingdom points with two different Use Years and I always wish they were together. I get by and make it work, but it is just an extra hassle.
I would NOT recommend buying the additional points at BCV or Riviera. 50 points scattered out here and there just IS NOT ENOUGH to be comfortable with. At 7 months to 11 months you would have to book at two different resorts and only try to combine them into one resort after 7 months, and by that point EVERYONE else is booking, too, and it is hard.
I say this from experience. I have over 1000 points at 3 different resorts (AK, Poly and BLT) so I have enough to play around with and I can ALWAYS get something I like, BUT, I have a lot of points. If I had less, I can see exactly how hard it would be.
Trust me on this. Get the same resort and Use Year.