I’m leaving for 19D OSUT on the 4th of November. What advice do you have for me?

Ill give you something a platoon sergeant told us once, and it really applies to your whole career.

Do what you're told,
Do what you're told,
Damn it, do what you're told!

Keep a good attitude;
Stay motivated, and motivate your peers;
Figure out how to read the daily training schedule, review it nightly, and use it to prep equipment and gear, identify any shortages or issues the night before and report them to your DS for a solution;
Have everyone work as a team, especially that asshole who never has thsirbahit ready, always tries to get out of work, and is an otherwise whiner.
Use all idol time to go over commonskills, get weapons assembly/disassembly competitions going and other related skills.
Take notes, write lessons learned.

Dont talk in formation... drink water... learn to get along with people who are hard to get along with and work as a team.... dont bag a scumbag and treat the place like high school i.e. every time the DS has their head turned you are doing your own thing and not what was put out.... make sure your boots fit (your feet will most likely experience some kind of pains) maybe go running with no socks in your shoes before you get there to help toughen your feet a little ... do what your told