gingerbreadger
Actually for most OPKs (clearblue digital smiley included), should not use FMU. The only one that can use FMU is the clearblue fertility monitor.
I am looking at my clearblue smiley instructions and they didn't advise to use FMU. They just said it is more convenient to test first thing in the morning and that we can test any time of the day. But from what I know and think other "experts" like lynzi has concurred, clearblue digital smiley should not use FMU.
SJX
I use those timeframes to test for twice a day. But I think if testing once a day, can be slightly flexible in timing. Hee...
Just something I found:
Should I use first morning urine (FMU) with OPK's?
No. LH is synthesized early in the day, and is not metabolized into your urine until later. So, as a rule, you are more likely to catch your surge later in the day. Using FMU may not be a problem for you, but if you do not detect a surge during the cycle you use FMU, try testing later during the next cycle.
Note: the Clearblue Fertility Monitor is the exception. The FM Monitor does require FMU.