this is all my feelings from having been where you are heading. It is based on my experience. It is opinion only and not gospel.
The best friends you will have will be other drivers, who will be able to help you with problems you will face daily. They will also be able to help you if you get stuck somehow on the board. Whoever you know as drivers, keep them close. Also if they think you are coming from the inside, to get six months and go full time, you likely will not get much help. The help you will get will be from mgmt in that case. Everyone thought I was an infiltrator, who wanted to sneak into the hourly ranks, and go running back to mgmt, with the goods. Nothing was further from the truth.
If you know the route you will be on, since you are now inside, see the loader, and find out how the truck is loaded. Being on the inside, you have the opportunity that others dont, if you are now in the building you will be driving out of. Take yourself out on the route, and familiarize yourself. If possible, take the day befores driver records, and you will see why he pulls where, and how it is run.
If you are not in good physical shape, start now or your body will be your worst enemy. Keep plenty of water with you, no matter the weather, you can dehydrate just as easily when it is 0 as when it is 100. Bring snacks. Cheese, bananas, broccoli, carrots. Try to stay away from heavy foods, til you adjust. Plan on devoting the first couple months to getting through this period and not much else. Tell your wife/husband , or sig other that they will be on the back burner, so you can get this job which pays so well. You dont need someone nagging you that they arent getting enough of your attention. They will have plenty of time to do that once you are permanent.
Learn to breathe, seriously, it is the best way to get control if you are getting stressed out. Talk to some of the women, or men who have been through natural child birth, they know the breathing techniques.
Good luck, keep us posted.