I was wondering that as well. I am pretty confused about the time frame, he said the book was released last summer and in it's first month made $10 and in it's

I was wondering that as well. I am pretty confused about the time frame, he said the book was released last summer and in it's first month made $10 and in it's 12th month make 40k. How can he know what the 12th month is if it hasn't been twelve months since the book was released? Am I missing something?