my %files = ('foo.txt' => [0,time()], 'bar.csv' => [0,time()]);
while(%files) {
  for(keys %files) {
     if((-s $_ == $files{$_}[0]) && 
          (time()-$files{$_}[1]>60)) {
        &move_file($_);
        delete $files{$_};
     } else {
        $files{$_} = [(-s $_),time()]; 
     }
     sleep 1;
  }
}