I just saw this post and am sharing it. I don’t know what the deadline is, but the nomination procedures are very specific and must be done at the link provided.
It seems as though you can nominate any Indie-published book.
I hope I make up my mind who and what to nominate before it’s too late.
Check it all out here: http://selfpublishingadvice.org/blog/read-an-indie-author-alli-book-of-the-month-awards/