Aulani or not, I wouldn't buy any DVC contract where you need to bank and borrow three years worth of points and still won't get a full week out of it. There are too many logistical hassles when it comes to booking and you leave yourself with zero flexibility.
Hypothetically, what happens to your perfectly calculated three year bank/borrow plan if the
points charts shift and your target dates get even slightly more expensive? What happens if the airline you prefer changes their flight plan and forces a date change?
I don't think it would be wise to pick something to "try" that you can only actually use once every 3 years because it's going to take you 6 years, which is an eternity, just to get two data points in your trial. This is much more of a commitment than just buying a contract in the first place that you can sell if you decide that Aulani isn't for you.
I also wouldn't mess with a split stay for your first trip. Because if something doesn't feel quite right about it, you're not going to know if it's because you didn't like the split stay or something about Aulani itself just wasn't for you. When we did our first Aulani trip, we learned that we wanted more nights, not fewer (started with 7 and our trips since have been 8). We just did the Big Island, also for 8 nights, and found that length to be perfect for us. Even though a 5/5 split stay is longer in total than a single 8 night stay, I think it feels much faster because you're not able to mentally unwind for the first half since you have to be prepared for the logistics of checking out and another flight, etc.
I'm not a fan of split stays, either at Aulani, or elsewhere. But when we go to Aulani from the east coast we do try to go out a couple of days before our Aulani stay begins. We spend a couple of nights in a Waikiki hotel for those two nights. It works to stretch the points and helps us adjust to Hawaii time.
A different perspective, especially with kids, is that we intentionally try *not* to fully adjust to Hawaii time. We take advantage of waking up super early, eating "dinner" during late lunch or happy hour windows, and getting to bed early as things start to shut down anyways. I feel that this makes the return home easier.