It doesn't appear that there is an analogue to cron
available by default on Haiku. There is a port of Cronie available for download.
Given the current state of Haiku's multi-user system, it may be tricky to get working with a default install, unless you do this:
useradd root passwd root
...and also make the file in /boot/apps/arfonzo-cronie/var/spool/cron
with your cron settings be called root
.