I've never run in anything below 25, but tomorrow I'm going to try to run outdoors, even though the WC will be 0.  I don't have any kind of special running suit for super-cold weather, but I do have one pair UA Coldgear running pants, and one LS UA Coldgear shirt.  i have some other running pants, and some LS cotton T-shirts.  I have wool socks, hats, neck gaiter, etc.

How many layers would be appropriate for this type of weather?  Any suggestions or advice would be really appreciated.  TIA!