Hello ! Well to know when to harvest you need to watch at the trichomes with a magnifier/loupe/scope to know their maturity. When most of the trichomes are milky/cloudy then you can think about harvest. The effect will also be different when trichomes are clear & milky you will have a clear/energetic high - mostly milky = balanced effect - milky & brown = couch lock effect. Now if you don't plan to buy a magnifier then use your method , and I think you've still got at least 2/3 weeks before harvest. I hope it will help you 😁👍