A few things to consider:
1. You are making a long-term purchase. Will you never be able to book more than 7 months in advance?? Even 10, 20 years from now? I undertsand that there may be circumstances in your life right now that would dictate you not being able to, but will that always be the circumstance?
2. If you truly do think that you will never be able to plan a vacation more than 7 months in advance, consider carefully buying on property(OKW,BWV,BCV,VWL,SSR) vs. off property(HH,VBR) in the event you have to eventually sell your conttact. What location do you think would be more popular & therefore fetch a better resale price? While VBR & HH are lovely resorts, something on WDW property may bring you a better return on your investment. OKW generally has pretty good per point pricing and the least expensive maintenance fees. Not to mention that it's a nice resort, with lovely large rooms, beautiful landscaping and nice pools and a golf course.
Best of luck with your decision.