use strict;
use warnings;

my @dates = <DATA>;

my %months = ('Jan' => 1,
              'Feb' => 2,
              'Dec' => 12,
             );

foreach my $str_date (@dates) {
    $str_date =~ /^\w*\s*\w*\s*(\w*)\s*(\d*).*(\d{4})$/;
    my($month, $day, $year) = ($1, $2, $3);
    my $date = sprintf("%4d%02d%02d", $year, $months{$month}, $day);

    if($date gt "20080228") {
        print $str_date;
    }
}

__DATA__
usage1    Thu Feb 28 17:30:47 2008
usage2    Fri Feb 29 03:55:22 2008
usage3    Fri Feb 29 04:00:46 2008
usage4    Fri Feb 29 04:10:48 2008

##</code><code>##

usage2    Fri Feb 29 03:55:22 2008
usage3    Fri Feb 29 04:00:46 2008
usage4    Fri Feb 29 04:10:48 2008