use strict;
use warnings;
use Data::Dumper;

my @sorted = map  { [ $_->[0], join( '/', @{$_}[1..3] ), $_->[4] ] }
             sort { $a->[3] <=> $b->[3] || $a->[0] <=> $b->[0] || $a->[2] <=> $b->[2] }
             map  { [ get_quarter( $_->[0] ), split( '/', $_->[0] ), $_->[1] ] }
             map  { [ split( /\s/, $_, 2 ) ] } <DATA>;

chomp @$_ foreach @sorted;

print Dumper \@sorted;

sub get_quarter  {
    my @quarters = qw( 3 3 4 4 4 1 1 1 2 2 2 3 );
    my ( $month ) = (split'/',$_[0])[0];
    $quarters[ $month - 1 ];
}

__DATA__
10/23/2000 data1 foo bar baz
11/19/2000 data2 some stuff
08/11/2001 data3 what the heck?
04/30/2001 data4 this is getting dull
01/01/2001 data5 ??