"Scott that is a very good question. It really depends on what industry you're in. Another thing you want to look at is the lifetime value of your customer. If you are selling hair loss products the lifetime value of your customer might be $1000 over a 4 year time span. So you can afford to spend a lot up front and will have a negative ROI up front with the idea in mind that you'll recapture that cost over the lifetime of the customer.

If you're selling wedding favors the life time value is going to be much smaller because most people buy wedding favors one time. So you would want to be making money and having a positive ROI on your advertising budget. But you might want to factor in how many people these woman who buy wedding favors will talk to. You would want to factor in the word of mouth factor of your customers.

But in most cases if you're spending money on advertising you should be getting sales almost immediately if you're doing it right. If you're not, or your budget is just killing you, it might be time to change strategy. Know your customer and their value before advertising." by Brian Kaldenberg

"I'm going to guess Kentucky, Syracuse, Texas, and I like Ohio State also. As an aside, how long would you expect to wait before seeing some real results with online marketing? When should you think about changing your strategy?" by Scott S