It's very hard to understand what the OP is having a problem with.
The checks from Rakuten are in fact sent out quarterly. They just recently went out because I got my check a couple of days ago.
@canteloupe, when you log into your Rakuten account, check your cash back balance. All of the rebates you have earned will show up there. If nothing from QVC is showing up, you need to contact Rakuten about it. Or you can look at your click-through history and see if you really went through them when you made your purchase. If you think they are at fault, they can check your history and will credit you immediately if the fault is their's but you won't get your check until about December.