If you bought the rock and had it shipped, its possible that it had some die off, actually very possible. Another possibility of not having any nitrites or nitrates yet is because the tank might still be in the amonia cycle. I hate to play devils advocate but i find it very hard to believe that a tank cycled in two weeks, even with aged and established live rock. Aerobic bacteria has to grow on the surface of the sand, the rock, the filters and all. Hopefully I am wrong and its cycled already. Good luck with your lawnmower blenny, I have one and he is very fun to watch eat. Interesting characters