Which bottle do you open?

I open ours first. Because it’ll already be open and ready to go - the white chilling and the red breathing.

I think I would regard what my friends brought as a present and give them the wine I had already provided at the meal. We have relations who are likely to come for a stay bringing a bottle of champagne, in which case we do somehow manage to have that with them!

We always open the bottle people bring as well as our own for them to try.

Mine

I should say pour ours first.

Ours first already chilled if white or opened if red

We use the wine that we’ve chosen to complement the meal and chilled or opened to breathe.
Unless our guests ask us to open their gift because it’s special or they want to try it, fine, we’re not precious about it.

What is more, when I am visiting friends and take a bottle of wine with me, I do not expect them to open it while I am there.

If its a special occasion and we take, say, a bottle of champagne, then we might hope it would be open but not otherwise

I usually say "Thank you that's lovely" But use the wine I had planned.

I always use the wine I've prepared for state of readiness.