If you don't let it update, there's not much point in having it!
Wise man !!!! ....
update as soon as you log on and say every 4 hours or so ..... this can often be set to automatic with most good protection systems .... and rem we are talking about keeping every element of your protection system up to date ..... antivirus ... firewall ... spyware and adware ..... email .... etc etc .....