Given that, with a few exceptions, APs have been on an upward trajectory for several years, I don’t expect that April will be any different. I can’t see them slashing APs only to hike them again in July, so I would expect ‘business as usual’ next quarter.
Given that the scheme continues to go downhill fast (unless you want an EV and / or something from the Far East) then, if something takes anyone’s fancy before July, and is in a position to order, I’d crack on and not delay but, as always, making sure that the dealer understands that you’d want any downward AP movements adjusted pre delivery. Obviously the right to cancel and re-order always remains as well.