I do declare variables in the smallest scope possible -- but I do also put them at the beginning of the block.

Either you have a lot of very small blocks, or you're contradicting yourself.

{
    my $foo;
    ...              # n1 lines
    $foo = bar();
    ...              # n2 lines
    print $foo;
}
[download]

Scope of $foo: n1 + n2 + 3 lines

{
    ...              # n1 lines
    my $foo = bar();
    ...              # n2 lines
    print $foo;
}
[download]

Scope of $foo: n2 + 2 lines.

Juerd # { site => 'juerd.nl', plp_site => 'plp.juerd.nl', do_not_use => 'spamtrap' }