I think the X supplies could be a bit more constrained than other iPhone launches, for a few weeks anyway. But Apple have proven pretty good at getting stock into consumers hands in the past.
I’d say keep checking your local stores, maybe setup an alert with stock Informer for local and online stock.
My iPhone 7+ JB last year was proving hard to get but thanks to stock Informer I snagged one pretty soon after launch at my local store. Even the staff seemed pretty surprised that they had a delivery of them at that point.
My 6+, ordered via the Apple website was a week earlier than scheduled too.
So you never know you might get lucky. Keep your pre-orders, but keep checking around, it can be worth it.