it seems like an alright size for 2 months, maybe on the small size, but i am guess thats because of the pot size. hard to judge by the picture, but the plant seems pretty healthy. flowering will be triggered by the light cycle. it needs to hit 12/12 before flowering starts.
also remember a plant will grow 2 or 3 times the size during flowering, so you may want to consider transplanting to a bigger pot if you want to yield as much as possible. also, does your plant experience much wind or rain? low stresses to the plant will cause it to grow thicker stems. try some minimal bending of the plant in order to trigger it to strengthen its stem so it can hold more bud.