I think each child is different.  I have a 6.5 yr SWCAH girl whose bone age is about 7.  For awhile we dosed just twice a day but I felt that there were some behavioral issues that might be associated with not getting enough so we switched to 3 times daily.  We initially dosed at 6:30, 1:00 and 8:30 but now that she is in school it was more difficult to do the 1:00 so she gets it at 7:30, 3:30 & 8:30 on the weekends I usually give her bedtime dose a bit later to take her further in the night.  We have not seen any issues and her Endo feels that it is better to have that overlap than to be without.

Like I said each child is different, some are more sensitive with the Cortef so it is really trial and error (hopefully more trial than error!).  I would try the 3:30 and do a level check at your next appointment and see how the numbers are holding.

Good luck, prayers,

Stacy