Need help on dripping 700 emails over 20 days between 9-5 pm only

I have access to cron and config.php.

I’d like to setup an install of phplist to send 700 emails spread out over 20 days with sending only occurring during regular business hours. The emails should be spread evenly over the alloted timeslots of 9-5 pm over the 20 days.

I can’t seem to get this to work by hacking together the following in any combination of configurations together with cron jobs. Any advise much appreciated: