use DateTime;
use DateTime::Format::Strptime;

my @start_date = qw(01-06-2007 01-08-2006 01-06-2006 01-07-2007 06-01-2007);

my $Strptime = new DateTime::Format::Strptime( pattern => '%d-%m-%Y' );

my @start_datetimes;
foreach my $datetime ( @start_date ) {
	push  @start_datetimes, $Strptime->parse_datetime( $datetime );
	print $start_datetimes[-1]->ymd('-');
}

print "-"x10;

my @sort_datetimes =
	map  { $_->[0]             }
	sort { $a->[1] <=> $b->[1] }
	map  { [ $_, $_->epoch ]   }
	@start_datetimes;

print $_->ymd('-') foreach @sort_datetimes;

__OUTPUT__
2007-06-01
2006-08-01
2006-06-01
2007-07-01
2007-01-06
----------
2006-06-01
2006-08-01
2007-01-06
2007-06-01
2007-07-01