Timeframe to drop separation packet

I know this has been answered in a relatively recent thread, but I can't find it after 10 minutes of searching. What is the minimum amount of time from one's ADSO necessary in order to drop a separation packet? I've heard you can do it up to 12 months out. Is this accurate? Most people seem to do it around the 6 month mark.
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums