yeah, 1st session.
with 2 tomoe, you can copy and predict motions, anylize and understand more of the fightt, and you can also track handseals. 2 tomoe can see through C-rank gen.
with 3 tomoe, you can do all of the things 2 tomoe had, but everything is in slow mo, so you can see what is happening easier, you can copy handseals, repeating them prefectly, and can see through B-rank Gen. you can also use 3 tomoe, to cast special genjutsu