I echo the others - I would not try to let the mixture incubate in any way; I would just start making the cheese. The one and only time that I was able to use raw milk, I used it in a 1:1 ratio with store-bought P&H milk (i.e., 2 gallons of raw + 2 gallons of P&H). AND I vat-pasteurized the raw milk before using (held at 140°F for 30 minutes), because the raw milk had been transported across state lines (shhh, don't tell anyone!) to a friend, and then transported to me a day or two later - with all of this transportation and uncertainty about the handling of the milk at each step, I thought it best to pasteurize. Even with the pasteurization, however, the difference in using the 1:1 mixture vs. just using P&H milk was remarkable - both in the way the formation and strength of curds and in the taste of the aged cheese. I dearly wish I could readily get my hands on raw milk on a consistent AND affordable basis ...