Thank you! I'm super excited about having him but super nervous about having 3 kids! I had my first two close together (not as close as yours) and it was amazing!
I'm due September 5th as well, during my 20week anatomy I was told just the same as you! Baby will arrive a week before if I have a full term baby. I had a C-section with my first, he arrived at 29weeks - my preemie will be 8months in a few day. I know you're worried, but there's really no telling when he or she arrives. Just prepare yourself.
BTW, I was told baby #2 will arrive early as well. I'm totally worried, 2 babies under the age of 1 and less than a year apart. I'm bracing myself, hopefully things works out.
Sorry if I wasn't able to answer your questions, BUT congrats :)