I started working for Werner earlier this year, (my first driving job), and what everyone has said thus far about orientation is accurate. You should be there 3-5 days, depending on the size of your class and what day of the week you start. You said you're starting on Monday so I would count on the full 5 days. After that, it's pretty much just waiting on your trainer.
Since other posters have already covered what to expect during those few days of orientation, I won't bore you by repeating them, but I would add that if you're wanting to set up direct deposit, be sure to bring a blank check or a direct deposit form from your bank. The recruiter may say you can do it with just the routing and account numbers, but they will demand something from the bank with those numbers on it when you show up. If you don't have it, expect to receive your checks on a "Rapid" prepaid card until you do.
With that said, I would strongly encourage you to think long and hard about what you actually want from your first job before you go with Werner on Monday. You said you want to do OTR because you want to see all 48 states and run all day. While I'm not saying it's impossible that will happen for you, I wouldn't count on it at Werner. I can tell you from personal experience that they don't do OTR the way a lot of people probably imagine it, at least not for newer solo drivers. Veteran and team drivers may get the longhaul experience but I never saw it. In my time with Werner, I never got West of I35 and I never got a single haul longer than 650 miles.
Maybe things will be different for you but I have heard other drivers complain about the same thing, so maybe not. Again, you might have a completely different experience, especially since you live out West, but I would advise you to go into it expecting to do regional/local work in a region/locality other than your own. Don't be surprised if you get mostly 200-300 mile hauls with frequent shags in between, then the occasional 600 mile run that will finally get you out of the region you're in, only to be followed up with a 600 mile run back to where you just left. Enter the 200-300's and shags again. If you're fine with that, Werner will be a perfect fit for you. I honestly can't say anything negative about them as a company.
If you have any other questions, feel free to send me a private message and I'll be glad to help