When can I file I-485 as a derivative?

The I-485 instruction says that: “the individual derivatives may file their Form I-485 adjustment of status applications concurrently with the Form I-485 for the principal applicant, or file the Form I-485 at anytime after the principal is approved, if a visa number is available”.

My wife file her I-140 and I-485 together in September 2005, and her I-485 is still pending, can I file my I-485 as a derivative NOW?
Thanks.