Almost all MSCs announce their payment terms on their website and it's often pretty easy to find. Questions about when and how a company pays will be almost always be covered in either the ICA or the company's guidelines for the particular shop that you will perform. Marketing Endeavors shows their payment terms in both places. For specific pay information for the shop you are performing for Marketing Endeavors, check the shop guidelines.
Below is quoted from the guidelines of the most recent shop I performed for them:
PAYMENT
"* Your Paypal account will be reimbursed within 60 days from the day your shop is finalized. We only pay through Paypal. The email address you have registered with us and for Paypal must match in order for payment to be processed. It is our only way of linking payments to shops completed. If 60 days passes and your Paypal account does not say “Pending,” then contact our billing coordinator at
jess@marketingendeavors.biz."