The history of executed commands is stored by your shell. Try adding something like this to you ~/.bashrc
export HISTTIMEFORMAT="%m/%d - %H:%M:%S: "
It will change the HISTTIMEFORMAT variable and bash will store a timestamp in its history accordingly. Then your history will look like this
487 08/16 - 16:12:01: cd Downloads
488 08/16 - 16:12:04: ls -a
489 08/16 - 16:12:37: cat README | less
490 08/16 - 16:12:58: pkg-config --list-all | grep webkit
491 08/16 - 16:13:04: history
Available identifiers are
%d - Day
%m - Month
%y - Year
%T - Time
%H - Hours
%M - Minutes
%S - Seconds
