If it helps, I planted two bands last September two weeks before our first early snowstorm. They both came through the winter beautifully and are both growing well this spring. I planted them deep and mulched around them and they stayed buried in snow which I think helped. August sounds like it would give them plenty of time to settle in. I am in a lot colder area than you so others may have better advice based on more experience with your zone.

I've planted bands in October with no problem. As Joey said, the key is plant deep and mulch.
I'm making a fall order, too, so I will be planting in September or October again this year. I don't winter protect anything.

The important date is when the ground freezes. Then you work backwards 6 or 8 weeks from there. This assumes your ground freezes, which I don't think is a given. So where you are, I definitely would not be planting in August, but wait until October/November.

Whatever you do, don't 'winter protect'. In an eastern 6b, that can kill roses as fast as anything.