About to start chemotherapy...

Yes, that sounds about right.  The times are on the machine if you are concerned.  As long as it says "ready" it's good to go and cold enough.  There were times it was a bit longer beforehand if they were really busy.  Just make sure you push it down in the middle every so often to make sure it stays connected to your scalp.  Sounds like your doing well if you've made it the three weeks with not much change.   :)
xoxoxox