I too have been confused regarding this issue.  According to NIH, with whom I basically bank all my CAH info on, said that whatever way the endo does it is fine, it just should be consistent.  The doc interprets the labs results based on whether you have medication in your system or not, time of day, etc.

NIH prefers to have the labs done fasting, no meds & around 8:00a.m. because they want to look at your adrenal function at the worse possible time.  Its hard to change endos so just hang in there!!