Monti's won't grow for a couple of months while they are adjusting to your tank.
Like any sps corals, they need high lighting, low nitrates, and plenty of calcium and magnesium to grow. Also, some have argued to feed oyster eggs periodically to an sps tank.
I've never fed oyster eggs before, and have always fed DT's Phytoplankton, however I have always had good results.