My tank took about 2 weeks. The Ammonia spiked, then the Nitrate goes up, then the nitrites.
Once they all go back down to undetectable levels again, do your 10% water change and then you can add fish.
Damels are not a good choice because they are very aggressive and people buy them because they are hardy enough to live though mild-moderate cycles. They are bought to help get the cycle going.
Reading posts on here and books, once you're LR and LS are in the tank, and the natural decay of the LR should be enough to trigger the ammonia spike, that makes a form of bacteria begin to grow that digests the ammonia, that then makes nitrate as a by product, then another form of bacteria grow to digest that to make nitrite. Then the last form of bacteria grows to digest that and turn that into nitrogen which appear as air bubbles in your sand layer and then that is released as it rises out the sand, into the air.
Thats my take on it all. All I read suggests that damsels end up being more trouble than help in the end, unless you just dispose of them, I went and bought some reef cleaners, like crabs and snails, let them in over week two, monitored the chems every other day, and I was all set. I have read some fish food will help get the ammonia spike or even a raw dead shrimp from the grocery store.
The ammonia is only phase one. You need to get the bacterial colonies established to digest that, then the nitrates and nitrites,.
My chems dropped to undetectable week two using LR and LS, and the tank is doing great.
dont take my words as gospel, I've set up just this one tank so far but I did much research in books, and on here.
here is some picts of my tank
http://www.davidroth.ws/tankpicts/default.html
Good Luck.
David