It is way too dependant on the coral. Some you will notice the growth in the first month, some it will be killing you. Fot a frag to turn into a colony may take a little bit.
Monti Cap and
Monti Digi grow pretty quick, I think some of the ones I grabbed are slow growers, but they are real nice. The frag of
orange monti on the other hand you can notice the growth in pics that are different from like 3 weeks time.
Your calcium and other conditions will make a difference too. The more SPS you have the more calcium suppliments will come into play, but make sure your testing ifyour dosing, this applies to dosing anything. I have small tanks so I just use B Ionic, no reactor.