A few points:
1. If you have an existing contract with an April Use Year, generally speaking
DVC will only sell you add-on points with that same Use Year. If you buy 150 or more as your "add-on", they will allow you to specify a different Use Year, but for any amount less than that, the UY must be the same.
2. Since you mentioned booking OKW at 11 months, just be aware that you can only use the number of points that you actually OWN at a given resort to book at 11 months. If you add 50 pts at OKW, you can only use those 50 pts to book at 11 months. You'll have to wait until the 7 month window to book with your VB points.
3. Just a word of caution regarding Vero points. If you plan on staying at VB, they can be invaluable. I've heard it can be very difficult to stay there during some of the summer months unless you are an owner. But, if you're just seeing Vero as potentially a low-cost way to get into the program, I'd suggest you look at the maintenance fees. While Vero resales may run several dollars cheaper than, say, OKW, their maintenance is about $1 more per point, per year. I suspect you'll make up that difference (and then some) in just a few short years.
Vero got hit pretty hard by a couple of the hurricanes last fall, and I've heard there may even be a special assessment charged to members to cover repair costs. Buyer beware.