It's odd, even testosterone injections take a few weeks to induce benefits: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3188848/
I noticed benefits on the first day, but it was subtle and I didn't attribute it to Tribulus. But after a few days it became clear Tribulus was indeed the cause.
Yeah, I definitely noticed a decrease in stress response and recovery. It's like an adaptogen, stress doesn't get eliminated, I just feel slightly more resilient to it. Interestingly, this effect has remained relatively stable compared to the others. Not even traditional adaptogens, like Rhodiola, last this long.
I haven't noticed improved libido nor a manly feeling. I guess my testosterone levels are too low for that.