To get that early morning start, because the Sé doesn’t open until 9 am, go the day before, and before your friend arrives, and ask for two
credenciales. They can only say no, but I think you’ll get them and they are prestamped as
@henrythedog said.
The last time we were in Porto, I bought an extra
credencial for my deceased father-in-law at the Sé whom we walked the Camino
vicarie pro. It was meaningful for us to collect stamps for him along The Way including a final stamp at the Pilgrim’s Office in Santiago but one different from the one’s my wife and I received for completing the Camino. This
credencial was then given to my mother-in-law.
On our first trip to Porto our plane was 12 hours late getting to the city. Picking up our
credenciales after the Sé opened really put us on the trail much later than we had hoped. So, with a bit of luck, you’ll be able to get them the day before so you can begin your Camino at the hour you planned. Bom Caminho!