It seems as though the first couple of times it took them longer to get me in just the right position. I had a really difficult time keeping my left arm in the position because of pain, so any delay was a bit of agony. They used a foam pad to help support my arm, and that did help. After a few times, they got faster and I will always remember.... 95 and 7.5 were my positions, and I could tell when I wasn't just right in the cradle...my back didn't feel "right". I even got to where I would tell them I didn't feel right, and they would recheck everything. A couple of times I needed to be moved just a fraction of an inch to make it perfect. So, to answer your question, yes, it can take while, but it is worth it in the long run to make certain you are in the perfect position before they zap you!
You will be surprised how quickly the weeks will go by. It is good to visit with the other folks who are waiting with you, to help keep your mind occupied, and to focus on others' needs at the same time. I got to where I felt very motherly of some 80+ year old gentlemen, even though I am 56. They were very sweet and a little scared, as we all are.
Take care, Jean in WA