just to corroborate, I kind of follow the principle that eltorrente has laid out.

But I do not make use of a pre-training drink. I also cannot drink while exercising. The reason being that I mainly train with clean and jerks and anything in my stomach makes me gurgle and it is hard to connect the elbows to the hips if my stomach has stuff in it. But I do an immediate post-training drink. I use a 2:1 (dextrose & maltodextrin: pea protein) ratio. It is suboptimal but I am not a body-builder, so it suits my needs--i.e., it is enough to help my body naturally adapt to the task without any undue sarcoplasmic hypertrophy.