Actoin conditions using opportunity close date

Hi,

In opportunities we want to trigger a reminder workflow via actions 2 business days prior to opportunity close date.

I understand that we have to create a reference object that takes factory calendar, time zone of user, etc. into consideration.

The problem I have is how I can determine the opportunity close date and make it available in my date profile for further calculations?

Any help is highly appreciated.

Thanks,

Juergen