Yes, I agree that standing back and letting the boys do it is the hard part.
Also difficult is trying to reign in adults who are "over anxious" to try to lend a hand to boy leaders who may not be doing things "right!" Our troop is blessed to have several (damned) engineers as parents, and I have had to find outlets for their organized energies which do not include having them take over the patrols.
Just remember, everything is a learning experience for boy leaders. In case of problems, praise performance first, then ask how things might have been done a little differently to prevent "it" from happening again.
Relax, you will do fine. And if not, give someone on the list a shout. We're here to help.