Experience means different things. Sometime after that first year you should start to notice the job starting to seem easier for you. You will slip that blind side back in with switch tractors swarming about with little thought. You will start to drive from instinct not nervous energy. And you will start to notice what I call a 6th sense that will keep you from doing foolish things. Not everybody will do this.
I'm Not a new driver here , but as a smart driver you always keep the attitude that something new can , and will happen at any second , never let yourself become overconfident / complacent. You'll keep gaining experience with each rotation of the truck you're driving wheels. The experience learning never ever stops. When it does , its time to retire.
Use those uniforms as toilet paper and then turn them in so they don't keep yor last check. Some companies have strict uniform return policies
The way your question is worded, when do you have experience? at day 1, you have one day of experience. and so on, and on. If your question is when can you claim your an experienced driver, There really is no good answer to that. I go by years, as in, I have 6 years experience. But, and it's it a big but, you will never reach a point where you have seen and done it all. It will get easyer, but the biggest mistake in my eyes would be the point where one says to ones self, Self, I got this, no big deal! because that would be about the time that all hell would break loose, and the manure would hit the fan.
Not quite sure how to put this but an old saying comes to "I'm not young enough to know it all" Somewhere between 2 and 5 years most will start to get over confident. Not all, some will get that earlier and some even later but at some point it will happen to the majority of drivers. Then something will happen to remind them just how much they don't know. Not sure what you mean by 'THE EXPERIENCE' but you'll never stop gaining experience. Hopefully you'll never stop learning either.
As a boy growing up I pulled the handle of a red devil come-a-long many times,trying to get a 1960 International B170 in places it couldn't go on its own with a 1940's Bucyrus 21-W drill rig on the back. Every little thing I learned I remembered, still adding to those files in my head. I notice at times I learn from those that are younger who learned from someone older. I also notice that the "Know it all" tends to end up with bigger problems, sooner or later.