Heh, well in the sciences interpreting and analyzing the data is 9/10th of the battle.
I just re-read the Twitter DM I got from T-Mobile when I inquired about the pre-orders on March 29. It says "With any launch there is always the possibility that demand could exceed the available supply...Once you complete your pre-order you are locked into your place in line, so if there were any delays in shipping, yours would be shipped before people who placed the order after you."
The way I read this, the "first come, first serve" policy pertains to delays in shipping beyond the planned ship date. Why T-Mobile would NOT just ship the phones the moment they are paid for is beyond me. After all, crazy people like me who wake up at 6:30 AM just to pre-order a phone are also going to be showing it off to friends, coworkers, etc. and basically giving Samsung free advertising. One would think that Samsung wants the general public to be looking at the Galaxy S8 in action prior to the official launch. But I'm not in marketing, so what the heck do I know?
Like everyone else here, I'm going to be spending all of next week compulsively refreshing the UPS page on my mobile browser and generally acting like a crack addict. However, intellectually I'm fairly certain I won't have my phone until the 20th or maybe even the 21st. God forbid, I'm slightly worried that the aforementioned "delays in shipping" may cause me to get my phone as late as the 22nd or 24th! It's a remote but distinct possibility given that on the T-Mobile app we've all seen that ominous message "Estimated to ship 04/20/2017 - 04/21/2017."
I genuinely hope none of our S8s get delayed and stuck in transit over the weekend of the 21st. Otherwise I suspect that several of us are going to get arrested for breaking in to various UPS distribution centers.