You are a good researcher, I know...but it looks like the SF-180 is asking for your best guess, not requiring perfection. And there is a phone number and they do rush orders.
"Emergency" Requests and Deadlines
If your request is urgent (e.g. upcoming surgery, funeral, etc.) and there is a deadline associated with your request, please provide this information in the
"Comments" section of
eVetrecs or in the
"Purpose" section of the
SF-180 and fax it to our Customer Service Team at (314) 801-0764.
Our goal is to complete all urgent requests within two working days. Please contact our customer service staff at
(314) 801-0800 if you have questions or require same day service. Due to the large number of calls we receive at this number, hold times are often long. However, once you reach a technician they will be happy to assist you with emergency service.
http://www.archives.gov/veterans/military-service-records/#required.