Run a command every week with Cron?

That should do it:

5 8 * * 6 <user> <command>

or for readability

5 8 * * Sat <user> <command>

documentation (man 5 crontab):

              field          allowed values
              -----          --------------
              minute         0-59
              hour           0-23
              day of month   1-31
              month          1-12 (or names, see below)
              day of week    0-7 (0 or 7 is Sun, or use names)

Sat 8:05AM run find

# Minute   Hour   Day of Month       Month          Day of Week        Command    
# (0-59)  (0-23)     (1-31)    (1-12 or Jan-Dec)  (0-6 or Sun-Sat)                
    5       8          *             *                Sat              /usr/bin/find

These answers are all correct, if you are unaware of how to use cron in the future, use one of many cron generators:

• http://www.cronmaker.com/
• http://www.crontab-generator.org/