Hey there, I hope I'm not too late but wanted to make sure you knew I read your thread
For AIM 6:
Sign on, then click on the top of your buddylist on the Edit menu, then click on settings at the very bottom of that menu. Click on the very top tab on the left-hand side and make sure there's a checkmark beside "Display timestamp on IMs". Now click on Save at the very bottom.
For AIM 5:
Sign on, then click on the top of your buddylist on My AIM>edit options>edit preferences. On the left-hand side, click on IM/Chat. Now on the left column of the right-hand side, put a checkmark beside "always view timestamp". Now click on OK at the very bottom.
There's not anything that automatically turns it on for you, unless someone makes a small application to do that. I can tell you where (for AIM 5) you'll have direct access to that setting for all screen names used on your computer.
First, exit AIM completely, or else the changes might not stick--on your buddylist you can hit the key combo control+shift+F4 and that will close it completely.
Go to start>run and type in regedit and hit enter. Now click through the plus symbols through this whole line:
HKEY_CURRENT_USER\Software\America Online\AOL Instant Messenger (TM)\CurrentVersion\Users\screen_name\IM
and then look to the right, in the IM folder, for View Timestamp and double-click on it. Change the 0 to a 1. You can browse for the other screen names and do the same, all in one spot! Be sure AIM is exited, as I mentioned above, or else you'll get frustrated when the changes you made didn't stick.