If you make a sale you will not see it for a few days. I know from personal experience. I used one of my own links to order something. I think I did it on a Thursday and the sale showed up the middle of the following week. I remember seeing something when I signed up about a week delay. Sorry I can't remember the details.
If you are going to test a Linkshare merchant with PPC, you need to run the test and wait at least 2 weeks to see what sales come in. Also, if speedy payment is an issue you may want to wait and see about that as it is dependant on the merchant and some take months to pay.