Using crontab to update Debian

[Paulo Henrique Baptista de Oliveira <baptista@cos.ufrj.br>]

    Hi Debian users,
    In my country (Brazil) I only have to pay one tax between 0:00 and
6:00 AM independent of call time.
I'm start thinking to get my home machine live at night and set crontab
to use pon or wvdial (I have two account, one with pon and other with
wvdial) and use /etc/ppp/ip-up.d/script_to_upgrade.
    Am I following the right path to solution?
    The script will be only:
    #!/bin/bash
    apt-get update
    apt-get dist-upgrade
    ?
    Have a nice day,        Paulo Henrique