I just had one approved today, but I have also had requests rejected sometimes. Just keep coming back to search for new products as often as you can, because you have to move fast to get one when it comes available.
Don't get discouraged, having a request rejected is nothing personal, it's just that lots of people request each available product and they only send out a few, like Ryuson said.
The one month waiting period thing refers to the rule that you can only receive one EF-sponsored review item every 30 days - it doesn't mean that if your request is accepted you have to wait 30 days for it to be sent out. My accepted requests have always been sent out on the same day or the next day.