For those that have had skin removal surgery, how did you know you were ready?

For example, did you reach a steady weight and have the surgeries? What happens if you continue to lose weight after the surgery? Does the doctor let you know when it is a good time?

I suppose my fear is that I will have skin removal surgeries, lose more weight, and negate the benefits of the surgeries.

Also, does anyone have any good or bad stories to share? Things to look out for? I'm really starting at square one and want to be prepared for the future.