You can do it last, but it might die on you unexpectedly. The Asus M5A97 R2.0 or the Gigabyte GA-970A-UD3P are good boards if you don't want to use crossfire/SLI. If you want to overclock (which I suggest you do for the FX-8320), go for the Gigabyte.
You don't need to upgrade your CPU as of now. So it's graphics card + motherboard.