that's a tough one to answer. every viv is different. your maintenance level goes down with the more microfauna you have. also, depends on what animals, if any you are going to put in there. in a properly built, well draining viv, you should be able to go a couple years before changing substrates.
It's not very difficult, grab yourself a couple cultures of springtails or isopods or both. Since your reptiles won't eat them, you can toss them in, they will reproduce in your viv. In a month or two you'll see them everywhere along to substrate. That was why i said it depends on animals. If you were going to house dart frogs, i would have recommended introducing the microfauna for at least a month before adding frogs.
As for links, there a lot of threads about microfauna on dendroboard and frogforum