%start{date-format}{time-format}% (using php date format) for example:
%start{M jS, Y}{ g:i:a}%*
This will output as June 17, 2012 11:00am
Shortcode: [eo_events]<a href="https://wordpress.stackexchange.com/questions/53851/%event_url%">%event_title%</a> on %start{M jS, Y}{ g:i:a}%, at %event_venue%[/eo_events]
Referance: Event Organiser