outdoor flowering question

ok so i will be doing my first grow this year and i am trying to gain as much knowledge as possible before the time comes to ensure that i pull a decent crop. one thing i was wondering, and this may sound stupid to some but im serious, when do outdoor marijuana plans start flowering and how do i know when this time comes. (so i know when to add the right nutrients) any input/advice is GREATLY appreciated.

around here, midwest us, late july early august is when flowering starts. you'll see pistils start shooting out all over and a nice burst of growth if its female. male you'll see balls and the growth spurt.

cool thanks buddy