I tried to find a definitive answer for you, but no luck. Instead I went with the example in the pod for REST::Google. Here's the example:

#!/usr/bin/perl

use strict;
use warnings;
use REST::Google;

REST::Google->service('http://ajax.googleapis.com/ajax/services/search
+/web');

REST::Google->http_referer('http://example.com');

my $res = REST::Google->new(
        q => 'perl regex',
        start => 4,
);

die "response status failure" if $res->responseStatus != 200;

my $data = $res->responseData;

use Data::Dumper::Concise;
warn Dumper ( $data );
[download]

OK. It gets a little tricky here. start => $start doesn't do anything except return an index of 0. So, I figured the problem was indeed the "start' value. As I understand it now, the start value is something like this:

0 = 0
1 = 4
2 = 8
3 = 12
4 = 16

As it stands, your start value is 0, so it returns 0. If you want the index for the 4th page, then

my $res = REST::Google->new(
          q = 'perl regex'
          start => 16,
);
[download]

It will give you an index for the fourth page.