Costco tmo site on preorder day

Does anyone have experience ordering iPhone on preorder day as soon as the window opens? The background is I am trying to get the iPhone duo at first moment of preorder so I can get it on release for a trip. I had horrible stories from back in the day where both Apple Store and T-Mobile site malfunction due to the high traffic. It’s been a few years since I last tried to get a phone on release so I heard Apple mostly patched up their store and very smooth now. But I don’t know how well the Costco site is as their app is sometimes bad with loading and crashing. Do I chance it to try to get it through Costco or take the safer route to go through Apple?