I prefer taking my carbs pre-workout. To me, waiting until your training is over is too late, and I've experienced better results with my current method. I usually drink about 60 g of dextrose - half just before walking onto the gym floor from the locker room, and the rest at the halfway point of my session.
I found out later that Dorian Yates employed similar practice. Milos Sarcev and Charles Poliquin also advocate pre as well as intra and post-workout supplementation.
