55-65 days it says it should be flowering for. That seems a bit early. Check out other ppls diaries to see when they harvested.
Most autos will be finished flowering in 45-55 days. So me, I'd give it a few more weeks. It needs it.
As for flushing. Well,, each to his own on that. Some do it, some don't. Me personally, I use synthetic nutrients with heavy metals, so I have to flush.
If you growing organic you best of just stopping the feed for a few days and let her finish eating with whats lefts in the substrate.
Check the trichomes. You want to me in the harvest window and hang dry it whole with at least 90% cloudy.
You still got a lot of white hairs and it's only been flowering 4 weeks but I don't know that beeeders autos so. Again check out the grows. But I'd say at least 2 more weeks.