My wife is in marketing for her day job and has been using that knowledge to help target and generate interest in her books, and it seems to be paying off, as her preorders are eclipsing quite a few established authors in the groups she's in, and this is her first book.
When she had half the preorders she does now, a friend was saying she could probably expect around $2k in sales in her first month, judging by the preorder numbers, so by the time it releases she might be seeing 2-3x or even more than that.