it depends on the complexity of the machine and the quality of the manuals. In 2007 I bought a Philips/Yamaha CSM84 P&P. It was a very simple machine, no vision, mechanical centering jaws on the nozzles. The manuals were pretty good, although not "perfect". I had it up and running in ONE WEEK and was making boards right after that. It came with some of the prior owner's board files, I picked those apart and wrote a translator to convert my CAD system's placement files to what it used.
Then, in 2020 I upgraded because the Philips machine was not accurate enough for fine pitch parts. I bought a Quad/Samsung QSA30A which is a much more complicated machine. It has a fiducial camera and alignment cameras on each nozzle. The machine had been tinkered with by monkeys and had sat for six years before I got it. it did not come with any manuals, I had to scrounge those up. Also, the operator's manual was absolutely AWFUL, it was just a guide through the GUI screens, and really had very LITTLE explanation of what went on inside the program. They didn't even describe the coordinate system. The machine's coordinate syste was +X to the right +Y away from operator. But, the BOARD's coordinate system was +X to the LEFT! Geez, there is some sense to this, as the stop the board is fixed against is at the front right edge, so coords increase away from the stop. But, they need to TELL you this! That's just one example of how much vital info was missing from the manual. Fortunately, I got hooked up with the guy who did the factory training on this machine, he was invaluable!
So, do they have the manuals? Can you take them home and do some reading? Is the machine a popular make/model, or something very uncommon? There is a web site smtnet that has both contract manufacturer pros and amateurs that are quite willing to help somebody get up to speed. I relied heavily on their advice back in 2007 when I was looking for a machine, and their advice was spot on.
Jon