Waiting for Rakuten cash back on the litterrobot website, is it worth it?

I have funds in my FSA that I can now use towards the litter robot. I know PetSmart can sometimes have a good cash back deal on Rakuten, but I would have to purchase directly on the litter robot website to expense it through my FSA. Are there any periods of higher cash back that litter robot does besides November or should I just purchase it ASAP?