If the tank is just getting past the cycle, I think it would be a little early to put in a lawnmower blenny unless you can ensure they have enough vegetation to eat. I added my blenny after most of the other fish and have had no problems with it. I have some algae and he has a fat belly. The advice of adding the more aggressive last is good. The others have set their territories. I have a royal gramma that I added after the clowns and I saw very little of it for 2 or 3 weeks. It stayed hidden in the rocks. Now it's out most of the time with the other fish. Based on that, I would think it should be one of the first to be introduced.