Wayne, what I've been told and read, you can't make a starter from DVI cultures. So it's pointless to rehydrate I would think. I just add them to the milk. As far as lag period figure it's freeze dried and unlike a regular starter culture which has living organisms already pumped up ready to go it needs time to start working. I personally add 30 minutes to any recipe for DVI. This has been confirmed, kind of, by recipes I've got from Egon at Danlac. His recipes for Parmesan, stilton and blue are all double ripening times from what my books say for regular starter.