Question re: preflowering on outside grow

I'm in the Northern Hemisphere and plants have been in the ground since late May/early June. They're growing steadily where they are. I'm wondering when plants will start to preflower outside in the Northern portion of the US (Zone 6)? I've been watching them carefully, but a guideline on timing would be helpful.

Thanks!

My plant isn't flowering yet, I'm in Seattle. I should probably check on it today. >.>

Mine are flowering for about 12-13 days. Both of them, at the same time, southern california.