Sign up for shops on their website, not by emailing them.
They have their own timeline for actual shop schedules. If you go to their website and sign up for shops, they may not actually need the shops done for a few weeks, and sometimes shops will give very long times within which the shop can be done.
It may be weeks later that they contact a shopper who expressed interest--and at that point they will make the assignment. For them it is normal. Unlike other MS companies, who might take a few hours or a day or two to make the assignment.
They have great shops with good fees, and they pay on time