While GHRP will stimulate the pituitary to release growth hormone, and GHRH will amplify the amount of the release, timing an exogenous HGH injection 30 min after your GHRP/GHRH dose can significantly increase the pulse associated during this time, not only will overall serum levels be higher, but the release of Free Fatty Acids will be faster and in greater numbers. Also doing so this way, your body has no way to tell that you supplied additional HGH to the natural pulse you fooled your body into producing, leaving your pituitary at 100% function.
What will happen, is the GHRH and GHRP dose will rise and peak after 30-45 min, once it peaks it will SLOWLY decline over the course of 3 hours, if you supply the exogenous HGH 30 min after the GHRP/GHRH combo it will start to rise and peak 3 hours later, followed by a 3-5 hour decline. Essentially giving you a 6-7 hour highly elevated serum level. Score!
I'll see if I can find the studies on this, but in my own blood tests, and others I was able to measure both peaks. one test 30 min after dose, and another 3.5 hours later. Both ng/ml levels were very high and sustained.