It takes it about 2 week to a month to start showing new growth. Then it will go crazy on you. I have had some of it turn brown and hasn't recovered yet, but moss never truly dies. I just keep watering it and hoping for the best.

I even have some of their moss in a very wet boggy section and it is growing nicely there. Though I did grow it for a month before I put it down in the water so your results might vary lol.