Yes, please wait until the nitrites and ammonia are gone, best way to go to be safe for the fish.
Being you have ammonia you are well on your way. Assuming you didn't put it in there 🙂
My tank I have now I did a fishless cycle feeding it fish food to cycle, it took what seemed to be forever (even to get ammonia). This one did not get brown algae for quite a while after it had cycled, they are all different.
It now has very little brown, I think the pleco and Hillstream help the most.
Oh, I do run UV, that should help too.