XChat 2.8.8 does not have the facility to show the time of a message.
Please make that, when the mouse is hovered over the name of the poster, to display a popup with the time of his message.
Lian Wan Situ
You can enable time stamps in Preferences->Text box->Enable time stamps
Time stamps would better be displayed in popup baloons, not to take place on the screen. Also these popups should contain seconds by default.