SRM,
I got my EAD renewal card from Arlington office today. Mine was a different case tho, I have applied for my EAD renewal at Arlington on Jan. 8th.
I got the approval last week and they have given an appointment for today at noon. I just walked in.. they have asked for the residency proof, (that i either live in VA or DC, they want Driver's license or a utility bill with your name and virginia address). They took a photograph and gave me the card in 2 minutes...
No harm in trying for a walk in after 90 days after applying for renewal, with a proof of you living in VA.
Hope that helps.. and good luck!