When to say Bismillah

I know it sounds like a stupid question but we all know that we’re supposed to say bismillah before eating anything but let’s say that you say bismillah before you eat a meal and then you get up and we’re gone for like 5 minutes and then you come back to the food should we say bismillah again or just eat the food since you already said it. The same goes for drinking. Do I say bismillah to drink after I eat or just drink? Then say alhamduillah after drinking and eating ?