Those look pretty close to me. I have 6 different strains and all of them have been varying by a week or two. I'm in Colorado so not quite as cool as Michigan, but I set my Harvest date for next Friday for all 6 of mine. My plants also showed first signs early August. Since you're in a colder climate and a bit farther north you may have a bit different season than me, but I imagine Denver is a bit warmer than Michigan, so if I'm harvesting next week I'd get on it if you're in Michigan. Just watch the weather!!