This is what they call a "teachable moment". First, coming in early to "rearrange your truck" is stupid. Now you know why. First of all, it's against the contract. By the letter of the contract, a senior driver, could, and should file a grievance against you working. If your truck needs to be rearranged--it doesn't by you--that is bargaining work if supervisors would have approved it; and they wouldn't have. Second, if you make a mistake--not doing a pre-trip is YOUR mistake--your good intentions don't count for bupkis.
Slow down and do your job the right way. You learned your first lesson: if you make a mistake, they're gonna pin it on you, no matter how good of a job you're doing. Here's the thing about the pre-trip: it's important. And it is required by the DOT.
If you don't have time to do a through pre-trip, then you have too much work. If you're not checking your fuel, then it's safe to say you're not checking your oil everyday. Guess what? If your engine blows because it doesn't have any oil in it, it's gonna be on you, and you're gonna face an uphill battle when they threaten you with a bill for the engine. You need to be checking your windshield washer fluid, making sure your tires are properly inflated, making sure all of you lights are operating, making sure your horn works. And it doesn't happen often, but if you get pulled over for some reason, cops always want to see all of your registration papers and proof of insurance. You've checked that, right? Right?
You sound like you've written off this part of your job, and to be fair, when they train you, they breeze through all of this, but they go over it for a reason. They have to. It's an important part of your job. Look, breakdowns on the road happen. But a lot of breakdowns can be prevented before you hit the road. After you start to grow some whiskers, particularly if you always have the same truck, you'll know when something is off with your ride. If something's wrong, or you need to get oil, fuel, or get a tire replaced, then that is your number one priority.
Never forget that.
If that means you'll need help with air, then that's what it means. If you're not sure, error on the side of caution. It's a supervisor's job to try pressure you to say you don't need help. Guaranteed, that will be their first response. Get used to it, and learn to ignore it. If you're not sure, say you won't be able to get done by 10:30. Because guess what? If they push you, and say they don't have any help, and you cower down and say, "Okay, I'll probably get my airs delivered by 10:30", and you don't, it will be on you, and they will say, "You should've said you couldn't get done." And you'll get a warning letter. That's how these clowns operate.
That's your teachable moment. It's ALWAYS on you. The pre-trip is the easiest part of your day. Get it where you treat it the same as you do when you're figuring out your airs. Never make it easy on the suits. They are lazy at heart, and if they have to do some real work, they'll probably leave you alone.