October 1st might be a tad soon, but it will be close. If you harvest before she's ready you'll lose yield, flavor and the effects will be 'different'.

Why the time limit if you are continuing with re-veg and clones? Is this a homework project...? (kidding)

Is your tapwater 6.2 from the tap, or are you adjusting it down? Nutrients tend to lower the ph further, which might pull you below acceptable range, depending on your medium.