How do I append a date time stamp to this file name

I have a perl script that creates a text file.  I need to append the current date to the file name.  Right now, I have a variable like this:

# csv path/filename
my $csvfile = "/home/mydirectory/cron/shipping.txt";

It creates a file name called shipping.txt in that directory.  I'd like the filename to be like this:

shipping 20070912.txtStart Free Trial