Consular processing after I140 ?

My wife lives with a H1B in the USA. Although I own a H4, but live in Germany. Currently it is not possible to move to the USA for organizational reasons. Her employer wants to sponsor her a green card. PERM has been approved and within a few days the I-140 petition is due to be submitted. I am to be included in this petition as a dependent.

Because I am in Germany, my own green card is to be applied for via the consular procedure, so that my wife would be my sponsor. That said the involved immigration lawyer.

My question: When can the consular procedure be filed? If the I-140 petition was approved? Or must the I-485 (Adjustment of status) have been approved?