In all my previous transactions with Apple (online) ... I’ve always been charged immediately, and there’s never been an exception to that ... not even one time.
And, I’ve even bought a product online (from the online store, not an Apple product) which I asked to pick it up in the store ... and even though the products were not available for me to pick up in the store until several days later (I seem to remember 5 days) ... I was charged immediately.
I’ve NEVER ONCE in all my years with Apple ever had the charge delayed on anything I’ve bought from them or the online store.
So, I’m talking from my own direct experience. The only thing I can say about THIS ... is that what you say is TOTALLY DIFFERENT from every one of my prior purchases.
Pre-sales are handles differently. The products are not ready for shipment and Apple will not charge your card until they are ready to ship. They will charge your card when they ship. I have done this before.