I know we dont know the exact Date it all started, or the exact dates people died, people met etc, so we could do it by month i guess, also the comic sometimes drops small hints about how much times has passed, would it be worth having a quick read thru of the awesome comic to see if we can work something out? Also just for fun we could get a google map image of southern america and do a timeline of Ricks journey with it?  It would be guess work but we could get it as close as possible with the info we know, anyone interested?