Despite a new release, professional cover and increased promotion, this month has been a complete disaster.
My sales flat-lined from 4-12th September and again 14th to 30th; no KENP at all since September 15th.
An AMS campaign also started on 4th September but that might just be a coincidence.
September is the cruelest month--for KDP writers. Last year, a great August (for me) was followed by a pfft September.
Also, my AMS display ad campaigns are frozen, and I refuse to up my bid beyond a certain spot. I'm not even getting impressions. My AMS sponsored ads seem to be recovering from their freeze, but glacially. I wonder about doing another promo, but I think as Donna St. F. implies, now is not a really great time.
September 2017 has been my best Amazon sales month in a year or two. That said, I tend to associate September with black holes -- I remember at least two of them where sales vanished for a week or more and never came back.
(Don't trust KDP to publish a print edition. Don't trust CreateSpace to publish an ebook.)