im not really looking to build muscle on it. but id be aiming at muscle retention and fat loss. maybe 100mcg post workout and 100mcg before bed?
That would be effective. You're just looking to enhance the naturally occurring pulses anyway, and those are two most significant pulse you just identified.
The PWO order of operations should be your GHRH (or GHRH/GHRP cocktail), and then wait at least 15 minutes before consuming your PWO drink. If the drink is pure protein you don't have to wait. If it's got carbs to boost PWO insulin you have to wait so the digestion doesn't blunt the GH wave.