Use throughout the day. But here's a thought.
I buy my own, in pure powder form, this allows me to formulate the amounts I prefer.
For example, pre workout I mix higher amounts of Arginine aakg, tyrosine, and taurine in a shake. During workouts I use them in a drink
Post workout I add allot of extra Glutamine.
I also formulate some awesome antioxidant caps, things you just can't buy in those combinations.