We were instructed by our endo to do the blood draw prior to their first morning dose (by 7:00am) and then give them thier meds. I'm not sure if this is 100% necessary, but I know the main key is that you are consistant with the time the blood draw occurs each time. Meaning, if you get it done at 3:00 in the afternoon, you should be consistant with that time. That is what I have been told, hope it helps.