Coral growth rate question

OK, with a very few exceptions, all of my Fall fest frags seem happy.  They have colored up perfectly, the polyps extend and the coral expands.
I test my water with dip strips twice a week, and on the weekends I get funky with the whole test kit....everything is dead where it should be.  I'm currently dosing calcium since I don't have my reactor working yet, but the water tests great, so I'm happy.  I do a 32 gallon water change once a week in a 340 gallon total system.  It did go for a long time without a water change because I had to get large enough moveable containers (rubber maid trash cans on dollies).
I've got a couple of zoas that have added a polyp or two, and my birdsnest has almost doubled in size.  But the trumpets, montis and other LPS look good, but haven't grown at all.
How long do I wait and watch before I should start trying to find a problem?