The payment time listed in your contract has no meaning in real life. It states a 30 day turnaround. What it doesn't state is that 30 days turns into 60, 90, and 120. If they finally deign to respond to one of your emails or answer the phone, expect to hear about how the clients haven't paid yet, so they can't pay you. (I tried telling that to the cable company, but they still turned off my service for some reason.)
Another issue I had was the missing/incomplete product information I got after they booked me. It came in bits and pieces, some of it didn't get to me until after I was supposed to be started! Then, I had to wait a couple more days so I could submit my recap--the woman I asked had NO IDEA what details to include or where/how to complete the recap.
This isn't my first circus in promotions; I know how things work. There are better agencies who don't dodge you when it's time to pay up. There are even more agencies who give you all of the information you need to do what the client wants. J.E. Nelson isn't one of those agencies.