As others have mentioned, I would recommend doing a LOT of research. The amount of time depends on your satisfaction with the quality of research. I did about 40 hours of research over 2 weeks, but I also knew a little about DVC from 5 years ago when I first explored it with my now-ex husband. (Still kicking myself for not convincing him to buy then).
I would suggest researching DVC until you have no more questions, a full understanding of how it works, and have slept on it for a while. One thing to do while researching is find the
point charts and "plan" your vacations. Pick dates (theoretically), and determine how much it will "cost" in points. Make different scenarios at different resorts. That will give you an idea of how many points you'll need. I would also emphasize that 90% of the time, at 4-5 months out, you're going to be looking at SSR, AKV or possibly OKW. Summer is busy time in Disney so that will cost you in points and availability, BUT you can probably get SSR. Fall is hard, because you have W&D in Nov. plus W&D Marathon Weekend and
MNSSHP in Sept-Oct. As an example, there is very little available for both of those times right now.
If you plan on going 3 out of 5 years, you "may" be able to get away with lower point contract, due to banking/borrowing. If you bank one year you would, in theory, have double the points available for the following year. BUT, if you did not go for 2 years in a row, you risk losing banked points.
My best recommendation, and what I did when deciding to buy, is to write down all your thoughts, questions, concerns, tentative travel plans, etc. Involve your spouse and kids in the brainstorming list of questions. Get their thoughts wants. It will do no good if you purchase a contract, are limited to staying at SSR or AKV, and your children and future grandchildren don't like either resort. Once you have your list of questions, start researching them. Post questions here, read articles and sites on banking/borrowing/renting/use year/restrictions on resale points, etc. As you research, more questions will arise. Write them down so the next time you have a research session, you can find those answers.
DVC is a long-term financial commitment. Keep in mind you will be paying annual dues of several hundred dollars each year and that amount will increase annually. Consider if your family is willing to make that commitment. Are you financing or paying cash? Financing will not make much sense since it will impact the cost savings of DVC, and saddle you with a monthly payment. Draw up different budgets based on annual dues for your home resort to determine the long-term financial commitment keeping in mind the cost of the trips (outside of accommodations, there are travel costs).
The most important question to ask yourself is WOULD you go to Disney anyway if you did NOT have DVC? If the answer is yes, then DVC is a viable option. If the answer is no, then you may want to reconsider DVC.
If you get overwhelmed or feel DVC is not right for you after researching, that's okay. Walk away from it and if the urge resurfaces, revisit it again. When I first researched DVC back in April, I was positive it was right for me (after talking to the sales person at Poly). Then I went home, researched for about 3 days and was dead set against it, feeling it was overkill for me, a single person, too much financial commitment, etc, not as much flexibility, etc. So I stopped researching and let it go. Then a few weeks later, the urge to revisit DVC came up and I looked at it again. After more research, I started to think differently about it due to the frequency of my trips revolving around RunDisney events. Then I spent nearly two weeks debating what home resort to buy into. I have another post I made about that, and thanks to the feedback, I ended up buying a large contract resale for VGF that I'm excited about, and a smaller contract direct from Disney at SSR.
Have you taken the "tour" at Disney for DVC? It's a wonderful experience, though only somewhat informative. You find more out researching on your own. Taking the tour is worth it to see some of the rooms in person, but be careful that your emotions don't run your decisions if you do take the tour. I recommend being fully prepared with knowledge about DVC before going on the tour, so you are less likely to succumb to emotions during what should be a strictly business transaction.
I hope I helped! Feel free to PM me or post here with any questions. Good luck!