[Octoman]

Pinantanjohn, all of the "rules" we follow are really just subjective guidelines. It's a good idea to have more rock, but each system is different. Any amount of rock provides more beneficial surface area for biological filtration. But having less rock limits the bioload you can put on the tank and limits the "safety factor" that protects you from a crash when something dies/decays in the tank.

It would be impossible to say if you have "enough" rock. There are too many other factors to consider like quality of the rock, how often you change water, bioload, other filtration methods, etc... More porous rock has greater surface area, you can do more frequent water changes to export more dissolved waste/nutrients. The most important thing with any system is to test frequently, always know what your water parameters are.

As far as the nitrifying bacteria go, they will be able to colonize rather quickly (~month). However, like Jnohs was saying, it can take up to a year before things (much more than just ammonia and nitrite) stabilize, and even then changes such as new rock, rearranging old rock, adding new fish/corals, etc... will upset the whole system again. Also, denitrifying bacteria (the ones that get rid of nitrate) can take much longer than a month to colonize.

IMO, the biggest advantage of true live sand is the meiofauna that comes with it. These are the worms, pods, and other tiny critters that are extremely important to a healthy sandbed. These don't come in the "live sand" that sits on the shelf at the LFS, but you could get some from a local reefer to seed your sand bed. The stuff on the shelf (such as aragalive) only has bacteria spores in it and IMO is not worth the $ because these spores and bacteria will be plentiful on your live rock and can seed the sand bed from there.