Walmart spark review program

I got an invite for spark review program 2 years ago i got couple of items to review but lately I barely get anything. On the rare times I get an email to try to request products to review they are all gone this happens 99% of the time. So I want to know how do you guys stay on track to click on the emails right away the moment they are sent to get the items? Do u know when they are going to send an email or how does this work ?