I usually add the unpublished hub after I've finished the text. But then I go looking for the right pictures, videos, etc. that I want. So I've been accidentally not writing and publishing in one sitting.
However, I didn't know that Google crawls my website before it's published. Does that mean people who viewed my hub would get a no longer available message?
Anyway, I usually finish up a hub towards the end of the day. I haven't noticed whether or not that affects how much immediate traffic I get.
However, your question did make me wonder what would happen if I checked keywords for an unpublished hub through pageview.com to see where the unpublished hub would land before I finished it. I know there are other ways to look for page rank, but I like that one for now.