Same as TaniaG. Right away after my husband got the case number and IIN, we could log on right away, filled out DS-261 and paid AOS bill. We are waiting for our IV bill now, but we've sent out our AOS and IV package (on the same day as we got welcome letter).
For everyone who is waiting for case number or IIN, it's better for you to prepare the next documents needed. Esp if it takes several day for you to get police certificate. Thank God I don't need to send out police cert since I am from Indonesia.
Good luck everyone! Please keep all of us updated.
