What you're looking for is the timestamp. To display timestamps within the IM window

1. Click the View menu in the IM window and select Timestamps.

To display timestamps within the Message Archive window:

1. Click the View Archive button in the Preferences window.
2. In the pop-up window, select View and select Show Timestamps.

However, remember that timestamps are based on the system time on your computer—which may or may not be right.

Note: The F2 key on your keyboard is a shortcut to show and hide the timestamp.