Kitzur Shulchan Aruch, Rabbi Shlomo Ganzfried
Chapter 39 : Laws Concerning Eating or Drinking Before the Meal
If before washing [for the meal], you intend to eat various food that will also be served during the meal, regardless whether these are foods that require an [extra] berachah [when eaten] during the meal, such as fruits, or if they are such foods that require no extra berachah [when eaten] during the meal, such as relishes, legumes or potatoes; and also if you intend to drink beverages (except for wine) before washing your hands, and you also intend to drink such beverages during the meal: there is a disagreement among rabbinic authorities, if what you eat or drink before washing your hands is exempt [from the after-berachah]. Some maintain that it is covered by the Birkas Hamazon, like the other food eaten during the meal, and others hold that the food eaten before washing the hands is not exempt with the Birkas Hamazon. Therefore it is best to avoid [the problem] by eating or drinking these things only before the meal, and say the after-berachah; and avoid eating or drinking them during the meal. If you did not recite the after-berachah before, you may say it during the meal or even after Birkas Hamazon. And if you do eat or drink these foods during the meal, after saying Birkas Hamazon, you should eat or drink something and say the after-berachah to exempt what you ate or drank before washing [your] hands.
If you intend to drink wine before washing your hands, even though you will not drink wine during the meal, nevertheless, some authorities hold since the wine serves to stimulate the appetite, it is considered part of the meal and is exempt with the Birkas Hamazon. Others hold [however] that even if you drink wine during the meal, nevertheless, the wine you drank before the meal is not exempt with Birkas Hamazon; therefore, you should refrain from drinking [wine] before washing your hands, unless you drink a cup of wine after Birkas Hamazon and say the concluding berachah, Al Hagefen, which will also exempt [the wine] you drank before washing your hands. If you intend to drink whiskey before the meal, whether you intend to drink whiskey during the meal or not, be careful not to drink a kazayis of whiskey before the meal [so that a concluding berachah is not required]. But if you do drink a kazayis or more it becomes a question whether a concluding berachah [should be said.]
If before washing the hands you intend to eat honey cake, egg kuchel, or something similar, for which the after-berachah, Al Hamichyah, is said, whether you eat such cake during the meal or not, nevertheless, they are exempt with the Birkas Hamazon (because Birkas Hamazon exempts Al Hamichyah.) This is true only if there is not a long delay between eating [the cake] and washing the hands. But if you must wait a long time you must first make the after-berachah Al Hamichyah on the cake you ate, even if you intend to eat the same kinds of cake during the meal.