One thing I have seen as a difference between raw and store bought milk is the amount of rennet you can use. For 2 gallon make I can use 1/4 tsp of single str veal rennet, but for store bought I have to use 5/16-3/8 tsp to get the same flocculation.
If you use 1/4 tsp of culture for 4 gallons of storebought milk, then I would suggest the same amount for raw milk...what you will see is your initial pH drop a bit sooner with the raw milk. If you have a pH meter, just keep an eye on your pH more often until you get used to it. If you dont use a meter, then you might consider reducing the innoculation time by 25% or so...but that's just what I experience with the raw milk I work with....your results my vary.