What is typical protocol for serving a wedding cake? How soon before the wedding do you arrive & set up? If paid to serve the cake, how exactly do you go about it? If they opt for you to not serve it, what do you do?
I'm new to serving protocol...lol

I NEVER serve the cake. I reserve the right to arrive 2 to 6 hours prior to the start of the reception. Set up the cake and leave and go do the next delivery.

It would be extremely odd in my part o f the world for the cake designer to stay and cut the cake. Around here, that's the caterer's job.

I used to sell a wedding cake package that included me staying and cutting the cake, but with so many brides having the reception at a hotel-type of place, they had the cake cutting covered ... so I stopped offering it. (I started it 20+ years ago as a marketing tool over the local bakery. I couldn't beat their price, so I beat their service.)

I cut my cakes *IF* they also buy a buffet from me ... so as leahs said, in that capacity, I'm the caterer and I cut the cake. I will cut cakes from other bakers/bakeries *IF* it's set up with me ahead of time.

As the norm, if you are supplying the cake, it's pretty unusual for the cake person to do more than just drop off the cake.

I like to drop the cake off at least an hour prior to when the first guest will arrive, and I have dropped them off 2-3 hours prior.