All themes here are unique. there are no cookie cutter themes and there is no settings for what you want. Whether or not author bylines, author profile, date stamps and/or timestamps are displayed is theme dependent. Some themes show the timestamps on posts and some don’t. Apparently you chose one that doesn’t. You have two options.
(1) Type in the time on each post.
(2) Switch to a theme that has this feature.
Themes with and without timestamps http://wpbtips.wordpress.com/2009/03/24/posting-time-displayed/