Don't base anything on the graduation date on your orders. Make no plans right after your graduation. I started in class 19 in Pensacola, and due to several things completely out of my control, I now have to finish up/start over up in Newport.
... it is highly common for 30%-60% of the people that start off in a class to graduate in a later class...
That 30-60% don't graduate with their class is true but don't let this scare you. The VAST majority of people who rolled out of my class either came in unprepared (In PFA failure), did something STUPID (posted on AW that they were going to sandbag the In PFA) or had a shitty attitude (If you suck at putting others needs before your own, you're gonna have a bad time).
Some people, like Godspeed, get seriously sick or injured by no fault of their own and it is just bad luck. Know that you are going to get sick at OCS; suck it up if you can, if not, it's OK to roll, take some time to get healthy and try again as long as you don't fall into the fat lazy H-er mentality. That being said, there are usually several quality people in the H class who are a valuable resource. Good luck to all of you.
PS, there have been some other threads with females asking for a female POV on OCS. As has been stated here before 98% of being a successful OCS grad is not expecting special treatment. The other 2% are issues that are gender specific and I'll be happy to give anyone who PMs me my $0.02 on what life is like for the "fairer sex" at OCS.