As soon as a guest mentions they will be having wine, if you know whether it is going to be a white, red, rose, or sparkling wine, go ahead and get the glasses to set on the table even if they have not yet indicated the brand of specific wine they will first be drinking.
When they indicate which bottle they want to purchase or have brought with them (to pay corkage), go ahead and get the wine glasses.
Place the correct glass from over the guest’s right shoulder onto the table by holding it on the stem. The exception to this is if there is not enough room around the table to get to the guest’s right side. In that case, you can pour from their left, or even have them pass their glass to you if too crowded to get to either side of them.
Remember, food is served from the left and removed from the right, but wine is poured from the right and glasses removed from the right.