Allowing a hub to sit unpublished for a while can help its hubscore rise from the default if your SEO is good, it doesn't harm the hub.
I sometimes wait, more often I have some work left to do on a hub and leave it unpublished for a time while I do some editing.
Sometimes I just publish. It is a matter of personal taste, but there is some fact to seeing an unpublished hubs, hubscore rise.
After a week or two however after publishing there is little difference in hubscore variations for hubs which have been held back and those which are published and edited live.