Easy solution: Choose store pickup.
When I wanted the 6 Plus, I didn't get a store pick up or pre-order reservation (website was down, and all that mess happened). I didn't settle for a bad shipping date. I called Apple on launch day, and a representative told me if I waited till midnight (the day after release), the store would get new stock and I could make a reservation for the 6 Plus. I did this and ended up getting it the next day.
Don't settle for a bad shipping date. If shipping dates get messed up, they will probably get messed up by weeks, and not days.
I'm choosing Store Pickup because I prefer that option from past experiences. Inventory will arrive daily and it will probably be better to wait an extra day (if this is needed at all) rather than waiting an extra week.
But this is all speculation. Since Apple has given a 2 week timeframe till launch, maybe supply will be enough, or maybe there isn't even enough demand for the watch. But, choose the watch you want and don't settle for anything other than it, because you will be wearing it everyday on your wrist and interacting with it a lot more than your phone.