From my experience I can tell that it can take up to a month from submitting the Bit till finally being published. This may vary because littleBits plans the publishing of Bits tactical etc.
For my RGB LED Bit, Andrew, of littleBits back then, asked me to use other music due to copyright claims etc. He kept me updated on the progress. Also if I wanted to change description text or images I could contact him for that.
For my NFC Bit, Dennis, of Bitlab back then, just kept me up to date on when they would publish it. Also I asked him to edit the description text and images for me.
For the Radio Bit, Syed directly contacted me that they would discuss it over the next week and after a month he mailed me again that the Bit is published.
For all my Bits I never got feedback and are just the way I designed them. LittleBits also wants the community to respond on the Bits etc. look at it from a different kind of view etc.
I think littleBits will only give feedback if there's some kind of good reason. Not specific to the design etc.
Hope that helped.