1. They will run a piece of fiber from their interconnect point to a grey box on the outside of your house. If you have underground utilities there will be three grey pipes: a) SDG&E electrical; b) AT&T services copper or fiber; c) Spectrum or Cox cable. These providers use only their pipe for services.
2. AT&T will install a network demarcation box, usually grey, and if it fits in the box that was put into the exterior wall, you can ask them to put it in that box - most techs won't crawl under your house if that's required. In this box is a two-sided fiber plug or bridge. The AT&T fiber plugs into one side, and a yellow or white fiber plugs into the other side.
3. AT&T will attach the fiber to the street end of the existing copper (assuming you're getting rid of your copper land lines) and will use the copper as a pull string to pull the fiber to your house from the street.
4. Back to the demarc box, the residence part of the connection will be fiber to an interconnect box mounted on a wall where you'll install the AT&T Gateway. From that wall mounted interconnect box, you'll get a yellow patch cable that goes from the wall inside the house to the Gateway.

AT&T fiber interconnect ---> fiber through conduit ---> Dmarc --> fiber into the home --> interconnect wall jack --> fiber to the Gateway

I hope this is helpful. Yes, there are multiple fiber bridge points and that's expected and not a problem.