Each tank is different, usually I say at least 4-6 months, but it all depends on your parameters, stability and husbandry. If your rock was in really good condition when you got it and cycled, and you can keep your parameters stable (weekly testing before waterchange and stable for at least two months doing so) through regular frequent water changes, it is doable with something like a bubble tip. But don't be hasty, as you'll regret it if it melts and nukes your tank. Something like a rock nem or maxi mini carpet may be tough as nails but it won't hoste a clown and not really what most look for when they think of anemones.
But all theory aside, when you say new tank and if your new to hobby, just don't do it till your params check out week after week, usually at least a 4 month old tank. remember the reefing mantra: only bad things happen fast