It depends on many factors: 1. What market your advertising? 2. Target Audience? 3. Where you adveristing? 4. Banner or Text ads? Answer those then we can give ya a better idea, but generally speaking, if you were for example to use adwords and dependant on your daily budget you should start to see traffic on the first day.
my earlier post spoke about being the publisher and not the advertiser...I need to learn about this myself...
Ok after reading that im a little confused, my post was in relation to YOU advertising rather than earning advertiser money for being a publisher. Might wanna clear that up
oops...forgive me...I re-read and realized that my post doesn't answer the question at all...please ignore it...