I work for Urban. What I can tell you is that some people do skip level 1 and just get a trainer kite and practice for 6-8 hrs on their own. If you take the level 1 ground course we let you borrow a trainer for 1-2 weeks so that you can get some practice in on your own time.
Personally I went the route of skiping the level 1 class (when I was learning) and just bought a trainer. I had lots of stunt kite experience as a kid, so it came naturally for me. Also, I wanted to have a trainer so that I could get friends interested in the sport by letting them fly my 3m trainer kite.
Many of my students come in without having done level 1, but I also have seen some of these students come in with really bad habits when flying the kite. Having taken the course means you learn the right way, and we do not have to spend time in the level 2 kiting course breaking any bad habits.
That being said, I tell most students the #1 thing that speeds up the learning curve (outside of knowing how to fly a stunt/traction kite) is wakeboarding experience. If you are a advanced wakeboarder, chances are that you will be up and riding at the end of level 2 kiting course...and you may not need level 3. It is rare, by the guys that do it have been wakeboarders. This is because riding the board is very natural if you are decent at wakeboarding.
Other skills that help are knowing the basics of sailing....because that is also what we are doing. We have to tack upwind to be able to jump..which takes us downwind very quickly. So, knowing what angles you can ride upwind, what sheeting in and out means and does, are all things that help as well.
My advice to you is do what you think is best for level 1, take the course or buy a trainer and practice. You can also watch videos on flying a trainer (and other skillz) ..as CJ pointed out.
Then take the Level 2 Kiting course.
During the course make it your goal that by the end of the level 2 course you will be able to know how to practice on your own:
1) safely for yourself and for anyone around you
2) self rescue if neccesary
3) confindent in the 2 above listed criteria
4) know what beaches and conditions are good for you to practice on your own
Then, if after the kiting course you might practice at Jetty a few times on your own...and if it doesn't click and you are not riding upwind after 6-8 hours of practice at jetty island, then come take the Level 3 course and get a jetski assist where we can tow you out 1 mile or so and let you practice riding back in, where we get you some consistant riding and work on solidifying the more intermediate upwind riding skillz.
At Urban Surf we are fully insured to teach at all the PNW beaches. We have alot of fun getting our students into this awesome sport...and I think our students have a blast out there learning with us as well. If you are over 21 this oftne includes a nice cold post session beer in the pontoon boat as well.
That being said, all of the local instructors are IKO certified and are awesome people....so no matter what decision you make for lessons, you will have a great time and be riding in no time.
I might also mention that Urban has the largest fleet of IKO certified instructors...so planning this late in the game, we are probably the easiest to still get a spot reserved in the next 2-3 weeks...which will probably have the best winds. Once we get real hot, like in the 90s everyday, the winds start to be lighter and not near as nice as they are right now in July.
Good luck and hope to see you out there.