Ignore the time you are given, just turn up around 10:30 or so and you'll go straight onboard.
Last month, we left our hotel in the Brickell area around 10:25 from memory and we were onboard and in the YC lounge about 30 mins later ...
The magnificent 'Pepe' met us right after security and had us onboard in record time, I'd hope your experience would be similar.