Book Shipping Schedules

So noticed that every month so far has had at least 1 book shipped out. July has 1 so far and 2 more scheduled.
Then august has 2, then suddenly there isn't anything for september and it skips to October for the Gal, bitches book.

Are there any books that are planned for september that haven't been up for pre order yet? or is it gonna be skipped entirely?

I have probably been spoiled by this trend of 1 book a month.