re: Late winter pre-emergent application:

Both are pre em's so don't do two apps of prodiamine and then another app of dimension. Do one and one. It's important to rotate herbicides, pesticides, and fungicides so prevent pest resistance.

If you can't remember if you did one do you remember when you would have done it. Just looking for a time frame. If you think you could have done one in October then you can do it in the next few weeks. If you possibly did it mid December then I would wait a little longer.