I'm an ocean away I know, but here in England it is the PoCo that would actually upgrade the service itself, and their engineers alone who are authorized to run anything on the line side of the meter.

For panel changes in general though, in my area the local utility will arrange for a disconnect and reconnect on the same day.

In fact if everything is ready to go without too much delay, the local engineers can usually be persuaded to hang around for a little while and save the customer a double call-out fee (particularly if offered a sandwich and a cup of coffee [Linked Image])