I have also been given incomplete answers on this. First, if you start an intense workout the body's initial response anti insulinic. Usually blood sugar rises along with GH and test and adrenaline with weight training for 30-45 minutes. Also catacholamine rises and it blunts the insulin response.
But blood sugar does move into muscle without insulin during training and for several hours after training, non-insulin mediated glucose transport is higher.
So I think the main reason for carbs pre workout is not to get insulin up as it is naturally BLUNTED by catacholamine, but to provide carbs for active transport into muscle. If insulin sensitivity was naturally high after a workout then people would get dangerously low blood sugars after training. This does happen for some runner I know, but not for weight trained individuals.
Anyway, it is first important to define your training. Is it low rep strength training, or sets of 8-20 in bodybuilding style? A powerlifter uses 70% to 90% more fatty acids to fuel muscle in training and might use as little as 10 grams of carbs from an hour of training while a bodybuilder might use up 75-100 grams of carbs in an hour and might get half of their energy from carbs. Muscles use almost all fatty acids at rest, but they don't like to grow if they are glycogen depleted.
Also the length of the workout would matter. At about an hour I think that GH and test are done and blood sugar would certainly start dropping.
I personally think then that you should come in to a workout with full glycogen which is more a product of your last 12 hours of eating than your last 1 hour. I think that you should then start taking carbs somewhere around 30-60 minutes after the first hard set in a workout depending on intensity and volume. By the time they hit you, GH and test are done.
Again, I have never received a complete answer to all of these. Is insulin secretion in response to food higher after training, is insulin sensitivity higher or is there simply continued non-insulin mediated glucose uptake in the recovery stage. Since I have known type I diabetics who have had blood sugars drop 2-4 hours AFTER a workout, I assume that it is mostly that there is more non-insulin mediated glucose uptake in the period after a workout.