It's highly unlikely AC is releasing April or May, that's not enough time for preorders + we haven't seen a thing about the game yet. The only thing I could see happening is that they release a bundle with a preorder code like what happened with Smash and even that's a stretch.
1. Launching Animal Crossing alongside a new Hardware model is a huge marketing activation for the game. Far bigger than a few months of pre-orders off the back of a trailer with a future release date.
2. Pre-orders are borderline irrelevant in the day and age of digital download making up the majority of sales, but for a casual mass market game that has evergreen appeal on a relatively new system... it's simply not a factor. Animal Crossing will sell far more copies post its 8 week new release window.
3. I believe we will see a Animal Crossing Direct in March, and that will give us 30 isn minutes of everything you could possibly want to know (and probably plenty we don't care about, if the Smash Directs are anything to go by...) to set the game up perfectly.