Looks good. Kind of looks like purple power plant. Now to determine the perfect harvest window you need to examine trichromes under a microscope 30 times or higher magnification. Now from looking at your gorgeous plant closely you are possibly a week and a half out. Best of luck.
I have two clones, one of I which I kept on 12/12 lighting cycle to experiment with miniature plant flowering. It looks really nice. I am going to harvest it soon. The first four pictures are of the clone at its present state. The second four are during the initial flowering stage.