I think a lot of people are thinking back to the FP+ days for strategies for initial bookings. I've given this a lot of thought; of course we won't know for sure until the first wave of test cases, but I'm reasonably sure - assuming the number of slots allocated per LL per hour per ride remains the same (and I suppose they could safely raise that a bit, knowing the total number of people in those lines has gone down since the
DAS overhaul) - that it will be easier to book what you want with this new system as opposed to FP+.
Why is that? It all comes down to how many people you're "competing" with. FP+ was free; not
everyone used it, but cost was not a factor, so at your date (let's say 60 days out as a resort guest) you were competing with every resort guest interested. Now, at your date, you're competing with (at the moment) only the resort guests
physically in the United States who are willing to pay for the service. That is going to weed out many, many people; as FP+ was free, scores of guests booked as many spots as they could, for every day of their stay, even if they weren't that interested in each experience. That simply will not happen when people have to pay for it; the folk willing to pay will be judicious with their selections, and skip days/parks when they don't think they'll need it.
Now, they may be planning on "holding back" enough spots to cancel this out, to release day of, but I still think charging for the service will drastically cut down the chaos of the FP+ windows. And they did hold back spots for day of release back then too.
Not saying this will be without challenges - or that it will be easier than Genie+ - just that I think (and hope) advance booking will be a lot less stressful than FP+.