Chopping a DDA at 79 days is going to give you some mighty speedy flowers. The norm used to be wait 100 days and harvest a DDA. Most of mine I harvested at 90 days. I suppose it's a matter of personal preference. And also the environment in which a plant is grown goes a long way to determining when it's ready to be harvested. No matter what size mine were, big or small they all looked the same around day 90.