How often do the blackberry servers check the personal POP3 accounts? One of my services does not offer auto-notification, so I guess blackberry would have to periodically check my account for new messages.
It should be instant. I get my POP3 emails off various accounts in less than 30 seconds. At most it makes maybe 45 secs to 1 minute. RIM uses push technology, unlike Apple or WinMo, so once an email hits your inbox it's automatically pushed to your phone instantly.