Yes, I think it was the second payment when the pool went in- it was 7!/2 years ago, so I am not too sure. Half was put down before the work started, and the rest when the pool went in the ground. I still had to pay for the rest of the concrete, which was separate from the quoted price of the pool. The pool went in on the same day. As soon as it was in they measured it to make sure it was level, then back filled around it and started to fill it right away. It was lifted in with a crane! It looked like a big bathtub. I know that it was then filled and then the pump was started up. It was a while before they did the concrete. It is really hard to remember the exact sequence - but I know it was really fast.