Cut when you feel like you have too much fat on you. Cut down to when you feel like you look good enough, or people say "my god you're too thin".
I assume you've been training less than a year, so, you need to concentrate on getting big. If you bulk cleanly you might be able to get to 170 and cut from there. That's still pretty small IMO. I'd suggest bulking until next summer, then start cutting so that you'll actually have something to show off.