Hi,
Thanks for using our plugins I can help out here.
To make this change you can follow our themer’s guide:
https://theeventscalendar.com/knowledgebase/themers-guide/
To move and edit this file in your child theme:
events-calendar-pro\src\views\pro\widgets\modules\single-event.php
Once there you want to replace this:
<span
class="list-dayname"><?php echo apply_filters( 'tribe-mini_helper_tribe_events_ajax_list_dayname', date_i18n( 'D', $postDate ), $postDate, $mini_cal_event_atts['class'] ); ?></span>
with this
<span
class="list-dayname"><?php echo apply_filters( 'tribe-mini_helper_tribe_events_ajax_list_dayname', date_i18n( 'M', $postDate ), $postDate, $mini_cal_event_atts['class'] ); ?></span>
That should do it.
Let me know how that works out.
Thanks