If you have a tank you should be testing your water parameters in order to keep your tank stable.
What size tank do you have? How long has it been established? What is it stocked with? How much of a biofilter (live rock) is in place? And most importantly, how often and how large of water changes?
Water changes is how we replenish the trace elements that are being depleted so routine water changes are essential.
There are no hard and fast rules to coraline algae growth. There are just too many variables. Some people have growth start relatively early while others go for years without establishing any noticable growth.
Many consider it to be a nuicense, myself included because once it grows, it doesn't stay on your rock, it grows on your glass and can be difficult to remove.