Well, your eyes are changing every 5 minutes because you are in the hot phase! Pretty soon, the measurements will be more consistent, and you will notice less variation from day to day. Deciding when you are in the cold phase, is pretty much dependent on those two variables, the objective measurements, and what you are experiencing. The very frustrating thing form me, was much concern about making a mistake when the hot phase was over, and basing further surgeries on eyes that still might be changing. So I wanted to wait a long time, even though I was so anxious to have the strabismus surgery, hoping to have less double vision. And it DID work! If you know anyone who has had the graft for lower eyelids, tell them to write!