I've had my GT-R wrapped 3 times by Trey. Great guy and a great group that he works with. The reason for the 3 wraps isn't due to anything wrong but more the fun in changing colors!
I also had my Brammo electric bike wrapped and one of my race helmets. I plan to have the Tesla Roadster done here in a bit, but like the stock look for so long hence the waiting.
In regards to paint correction. You actually do NOT want a brand new wax on it, due to making it harder for the film to stick. Just a normal wash before you bring it in. With that being said, I think he washed one of my cars for me before a wrap.
In regards of work, he is kinda known around town for being the guy that fixes other wraps issues. Everyone of my wraps people ask if its paint. He does a great great job and works hard.
Also my GT-R is track driven and takes a pounding but looks great with perfect paint underneath! When we had the old film off for the recent new one, I got to see the original black and it looked pristine! I also removed the wrap from the carbon fiber hood as I am selling it and getting a new vented one, and again perfect.
In regards to appointments, it can vary. I would just give him a call. In regards to turn around time, it just depends. If you just clear the front, it can be a day, whole body 3 days, crazy satin wrap with ghost images 1 week, custom Marlboro livery colors on a MP4-12c that he recently did...2 weeks?
Look at his flickr gallery linked on the website to see the cars that he has done.
Hope that helps. Should me a pm if you want more info and I'll give you my cell to call.
Bob
ps edited the post due to the terrible spelling and grammar! sorry