The answer depends on a couple of things:
Was the rock fully cured when you bought it? You say you brought it home so I assume you got it from LFS - how long was it out of water?
If it was fully cured and not out of water for more than an hour you will likely NOT have any problems.
If not - it depends on the size tank, how old it is and how much is already in it - but as stated above you will need to watch for any ammonia spike - if it hits .25 you may want to do a small water change (assuming you have something alive in tank - snails, shrimp, fish...)