I prefer waiting awhile, till I get decent traffic. It is also much easier to get listed in directories and do link exchange if you have got no ads on your page. Also when you only have a few users it could look more suspicious if a ad get clicked 10 times by the same user, then when you have 100's of users and somebody does that... (if you understand what I mean)
put some text links ads at start .. and banner or excessive advertising later ... money earned fromads can be used to advertise your website .. So have it from start .
Well as the great and powerful Shoe would say "wait awhile" But as for me, i dove in with ads...haha...I have about 1000 uniques a day on one of my sites and about 2000 a day on another. But im not makin much..yet.....
i usually get some traffic going then put up ads as once they are addicted unless you just put up annoying ads they will still come back