Alien Encounter closed in 2003, so 2003 or earlier.
Wait, no Carpets, so 2001 or earlier.
Now to find something that opened during the 1997-2001 period, and we can date the map.
Hmm...Martin's map offers Buzz, mine doesn't. Maybe Buzz wasn't around yet. This would date my map all the way to 1998 or 1997, so the first year of E-ride Nights. And earlier than Martin's map. Unless Buzz was later taken of the roster. (When the newness wore off and guests discovered Buzz sucks?)
Marni's map also doesn't offer Pirates, and mine does. But I have no idea why or when this change happened. Assuming my map is older, E-Ride Nights may have been subject to the decline by degrees management style of WDW - Pirates was at one point replaced by Buzz.
Characters also declined by degrees. In the earlier map, they are present in FL and TL, absent in Martin's map. Tsk.