I don't know about northern Virginia, But I would have expected something similar to England in terms of season, and it is summer and far too hot here to go moving things about, all the leaves would drop off at the very least. You want them to get established, and a lot of plants do most of their underground growth and settling in during the months when the top part is dormant, so planting in Autumn and giving them protection against frosts is not a terrible idea to my mind, tho someone with more local knowledge might say different. But I would wait until the top of the plant is settling down.
If you already have plants you could set them out and move them about to make sure you get exactly the right place when you do plant. Some plants may come as 'bare-rooted', in which case they are likely to be supplied at the correct time for planting. To my mind good nurseries wouldn't have plants for sale at the wrong time, but I bet some do.