use DateTime;

my $timezone     = 'UTC';
my $year         = 2012;
my $month        = 6;
my $day          = 12;
my $millisecond  = 3600000;  # 1.00 am

my $dt = DateTime->new(
    year       => $year,
    month      => $month,
    day        => $day,
    hour       => 0,
    minute     => 0,
    second     => 0,
    nanosecond => 0,
    time_zone  => $timezone,
)->add(
    nanoseconds => ($millisecond * 1_000_000),
);

print $dt;
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