Er... There was a nice timeline on the Net somewhere (I think I used it as the base for my own:
http://www.geocities.com/echaecha/ad...stimeline.html - ignore the colored parts (my own additions))
I think that 2e was 1368 DR onward; 1e was until 1358 DR or so (the Time of Troubles conveniently changed 1e rules to 2e rules); I think 3e was 1372 DR or so onward. (It's on the Net somewhere, anyway.)
In addition, 339 DR or so and previous used the Arcane Age rules (arcanists, etc.; spellcasters did not have to memorize spells to cast them), which were rather 2e-like, but after Netheril fell, rules (again, conveniently) reverted to 1e rules.