You have to take a look at stat, opendir, open and File::Find::Rule. By using those mentioned functions and module, you can achieve your target. As planetscape++ said, you have to try to write the code and post the code if you have any problem. Below is a sample code.

use strict;
use warnings;
use File::Find::Rule;

my ($filename, $giventime, $directoryname);

my @files = File::Find::Rule->file()
                              ->name( "$filename" )
                              ->ctime ("< $giventime")
                              ->in( "$directoryname" );
                              
for my $file (@files)
{
    open ($fh, '<', $file) or die ("$!");
}
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update: Added code