The average cycle last from 6-8 weeks going the method that you have gone. Yes you can add fish but you are limited to very hardy fish. tomatoe, cinnamon, clarks/clarkes, luanre wrasse(remember that these will get mean) will do well. Dont add angels, butterflys, anthises, tangs, or lion fish. A good rule of thumb when adding any new fish to a fish only tank is to add only half the amount in inches of fish to the tank that currently exists. ex: You have four damsels and they measure about 1 inch a piece. You can add 1 two inch fish or 2 1inch fish. There is max the tank and filtration will handle in the end. Take the gallonage of the tank and divid by two and that is the numbe in inches of fish you can have. Understand that inchs in fish is not an exact science and bigger fish have bigger bio-loads and waist