Thanks everyone for your replies. It looks like my best course is to wait until spring before I do anything. Hope there'll be regular grass on the lawn after the crabgrass is gone.
You need to get the pre-emergent down asap, keep seeds from germinating. You can use some weed killer with 2,4-D and quinclorac to take out what's there. But it'll brown and kill the crabgrass, which may or may not be better for what you are trying to do.
Pre-emergent needs to be done asap. At least that's what i'd tell you to do in Texas.
