From the look of your plant and going by the height of your room which you said is 80cms just under 1 metre.. your plant looks already half the heigh of the grow room, i have just grown white widow and they are flowering the widow grows at least double the size it was before you put it into flower, so it sounds like your gonna run out of space, but your plant is definatley ready to be put into flower if u can find a bigger space. If not don't worry to much, you can tie your plant down so its arched over, exposing more bud sites, and in the end getting more bud, or you could look into topping (but this stresses the plant, so id advise tieing it down). Anyways sorry for the bad news, good luck.

Happy Growing, Peace!