Is it worth starting a session at sunrise?

It is, very much so. Leaving before sunrise — early, genuinely early — lets us cover more locations in less time. The city has not woken up yet, and the time usually lost waiting becomes time spent shooting. It is the only way I know of gaining locations without making the session longer. To plan, I use apps that show where the sun rises and sets on any given day, location by location. That is not a technicality: it decides whether a viewpoint still has sun at six in the evening or is already in shadow. Then you choose the light. Golden hour and blue hour are different things, and not every location works in both. Timings and what each route covers are on the Porto photo session page.