Getting service in new construction

Reaching out here because other avenues have not worked. We are building a new house on a new street. Two houses total on the street. There is Xfinity at the end of the street and the electrician already laid the conduit underground for cables to be pulled through.  My builder has asked that I have Xfinity do this work now. However, the people I have spoken to at Xfinity don't want to schedule me until after we have closed on the house. Meanwhile, newly constructed houses on a new street very close by have not had this issue, so we know this is possible. Can someone help sort this out?