I wouldn't take it until you at least feel close to ready. However, I also think many of us could study Bio for months and may not cover some of the odd questions people are saying are showing up. I doubt you'll ever feel 100% ready. So you have to weigh the options. If you are not doing well on practice tests and feel like most concepts you come across you're shaky on, then wait. An earlier bad score doesn't help at all, and is actually probably worse than a better, later score. But if you feel like you're comfortable with most things, are doing well on practices, and are just stressing because of what everyone on here is saying, I don't think you should push it back. You would have to wait 3 months to retake and Nov would be pretty late in my opinion. Overall though you just have to do what is best for you and make a decision either way and stick with it. Don't get all caught up in the "it's harder, it's not harder, it's nothing like what I studied, Destroyer/Achiever/Topscore taught me all I need to know" stuff. Only you can figure out what you need to do.
