During the apéritif, serve one or two glasses to your guests. No more. The apéritif lasts at least 1 hour.
What do I say at the end of the apéritif ?
“On va passer à table”, “on passe à table”.
You must indicate where each guest will be. If you don't feel comfortable with all the vocabulary, just go close to each chair, and say “Monsieur xx”, “Pierre” ....
In France, most of the time, we bring the main dish served in a “plat de service” something nicer than a pot and the host serves his / her guests :
“Donnez-moi votre assiette”, “je vous sers”
You must also ask if anyone wants some more : “vous en voulez encore ?”, “je vous ressers ?”
Back to j'invite / I invite