>Is this possible please?
in a nutshell: no. the plugin allows to select from an available date/time according to your settings.
i would have thought that the vast majority of customers are not going to complain if its a few minutes earlier
but of course, you could somewhat adjust the labeling somewhat from the default
“When would you like to order for ?”
to
“When would you like to order by ? (we might be up to 15 minutes earlier)”
or something to that effect