The following example has a statement per line.

#!/usr/bin/perl -w
use strict;
use warnings;
use Time::Format 'time_format';

printf "Hello world, today is %s\n", time_format('mm dd yyyy',time);

exit;
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The following example has statements broken up into lines and is still valid:

#!/usr/bin/perl -w
use strict;
use warnings;
use Time::Format 
 'time_format';

printf "Hello world, today is %s\n",
 time_format(
  'mm dd yyyy', time
 );

exit;
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The following example is still valid but has unnacceptable formatting for human beings:

#!/usr/bin/perl -w

use 
strict;
use 
warnings;
use
Time::Format
'time_format';

        printf 
"Hello world, today is %s\n",
time_format(
    'mm dd yyyy',
time)
;

   exit
;
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The following example breaks:

#!/usr/bin/perl -w
use strict;
use warnings;
use Time::Format 'time_format'

printf "Hello world, today is %s\n", time_format('mm dd yyyy',time);

exit;
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Personally I use vim, set expandtab, and I break a long statement with new line and tab. If you foresee coding perl regularly, you need a copy of Perl Best Practices by Damian Conway.