I am not the fastest drinker and have taken to hiding my PDB under the blanket next to my hip when they collect them (and some FA's let you keep the PDB's and tell you to hold on to them, but that's the exception in my experience) and then I have a drink until in-flight service. This is probably a no-no and I probably should be embarrassed that I do it. It makes sense that C+ gets service first because they all usually do the cart prep and then push the carts out to the first row of C+ and then the First FA takes drink orders. Taking in-flight drink orders prior to take-off happened maybe twice last year out of nearly 100 flights, and maybe even just once.