Every blog post has publication date and time displayed at the top or bottom of the post contents in WordPress. By default, the_date() and the_time() functions are used to display date and time information respecitively. Majority of WordPress themes already contain these functions to display date and time details for every entry. You can easily change (and customize) date and time display format without any manual code changes.
Use different “Date & Time” format on WordPress site
1. Login into your WordPress Dashboard and goto Settings > General Settings. Scroll down and look for “Date Format” and “Time Format” sections on “General Settings” page.
2. Click to select either format that you want to use for date and time display. For example: date formats include: [September 25, 2012] , [2012/09/25] , [09/25/2012] , [25/09/2012]. You can also setup custom date format using: l, F j, Y.
Where, l = Full name for day of the week (lower-case L), F = Full name for the month, j = The day of the month, and Y = The year in 4 digits. (lower-case y gives the year’s last 2 digits).
3. Similarly, you can select and use either of exisiting time formats like [11:20 am] , [11:20 AM] , [11:20] or create custom format using: g, i, a strings. You can find more information for using combination strings for custom date and time format at official WordPress codex page.