I just purchased a new home from David Weekley in Houston.
My inspector told me that the the roof flashing is J-Flashing, which is not qualified now. The code asks the builder to use Step-Flashing instead of J-Flashing in Texas.

Our new home is supposed to close on next Friday. We haven't talked to the builder about this flashing problem yet. But I heard from the inspector that it is a little difficult for the buidler to change it. So what should I do? Ask the builder to delay the closing date and change the roof flashing from J-Flahsing to Step-Flashing? Or close the home first, and then ask the builder to change?

Step flashing has been the industry standard as long as I can remember back and as long as I have put on roofs since the mid 70's as a teenager. J channel is for siding edges.

You will have to consult the local code official in your town to verify what is an acceptable installation and is it code compliant.

There is a reason step flashing is the industry standard. Hopefully it has been resolved by now.