When I cold smoke sausage, its usually 6-8 hrs. I would assume, depending on your personal taste (how much smoke you want) that bacon would take longer depending on type of bacon and thickness.
The colour should be darker but will be hard to tell the difference unless you have another piece not smoked to compare it to.
I would say, belly bacon, with my taste, I would smoke 7-9 hrs in cold smoke.
Hope this helps.