When is service connection completed for water / sewer for new construction?
Typically, tie-ins are done in conjunction with the locality (town/city maintenance) and are done independently of the state inspections. This is because of locality-specific backflow prevention devices.

You see, hypothetically, nowhere in code do I need a backflow prevention device for sewer in my house in town. However, because I have a full basement, and my plumbing runs lower than the town's sewer system, it'd be in the best interest of all concerned for me to install one.

Get with your local contractor. He/she knows what to do.