I'd put both FHM and GSH in at the same time and let them multiply. Granted, most of my experience has been with ponds that have LMB, but I've never seen a pond that sustains a population of GSH where the GSH were put in after the predators were stocked.

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).