How many days are you planning to go to Disney? That may help determine whether you should go in May 2024 or at a later date.
For example, if you're only doing one day at each park, then you'll never be able to see and do everything, so May 2024 is as good a time as any. But if you're planning for 4+ days with the intention of trying to do everything, perhaps a later date would be better (although rides and other experiences are always closing for maintenance because they have very high standards, so whenever you go something that you wanted to do / experience is likely to be closed).
Fantasy Springs is going to be crazy busy for many years after opening. BATB and Soaring are both still extremely popular and they've been open for some time. So, unless you're willing to battle crowds and pay for Premier Access (if its available for some or all of the rides in Fantasy Springs), then when it opens probably isn't a huge factor. It's possible that entry to the area may even be "gated" like Nintendo World at Universal Studios Japan. I haven't read anything about that being proposed, but it seems like a possibility given the potential crowd levels.