Hi,
I think your issue is that your format is not supported by strtotime.
Try changing the if to:
<?php if ( strtotime( $today ) <= strtotime( get_sub_field( 'date', false ) ) ) { ?>
The second parameter of get_sub_field will return the date unformatted in the way it is saved by ACF (which is Y-m-d H:i:s) and will work with strtotime.
