use Date::Calc qw( Day_of_Week Delta_Days Today );
use List::Util qw( min );

my ($ty,$tm,$td) = Today();

for (...{ tasks }...) {
   my ($dy,$dm,$dd) = ...{ due date of task }...;

   my $delta = Delta_Days($ty,$tm,$td, $dy,$dm,$dd);
   next if $delta < 0;   # Don't care about past-due tasks.
   next if $delta > 14;  # Don't care about due dates that far ahead.

   my $ddow = Day_of_Week($dy,$dm,$dd);

   # $cc_super is true if this is the last
   # Wednesday or Friday before the due date.
   my $days_to_wed = (3 - $ddow) % 7;
   my $days_to_fri = (5 - $ddow) % 7;
   my $days_to_next = min $days_to_wed, $days_to_fri;
   my $cc_super = ( $delta > 0 && $delta <= $days_to_next );

   send_reminder($cc_super, ...);
}