density
pistils
trichomes
Use all three obervable characteristics with trichomes probably being the best indicator.
Based on image, the pistils look a bit long, so there's some ripening left for those calyxes. Get in there with a 30x scope and check out the trichomes. There are a wide range of suggestions as to how much amber you should see and this or that, so experiment until you find what you like.. don't depend on the whims of others for that.