i felt it easily within the first few days. the first 2 weeks were insane for me, strength went way up then it kinda tapered off after a couple weeks. endurance and recovery kept up the whole time.
i think it depends though, my friend is about the same stats as me and took it with me, he felt those effects in the last 2 weeks of his cycle and noticed very little in the beginning. ul feel ur strength rise quick if nothing else