I tried taking my gh at all different times over the course of the last 3 years or so. Never first thing in the morning on an empty stomach though (not sure why not). But have tried PRW, PWO and before bed. Can't say that either way has made a noticeable difference than the other except when I was doing Basskillers PRW with slin. Of course I'm sure the slin contributed to the better results but now and days I usually do it before bed.
There was a good thread over at AB on lean bulking by Argo, that I will be looking over and think about trying. It involves taking gh throughout the day and night with slin. Also a good thread about the best way to take gh for mass.