Even easier is to do it in quart mason jars imo after heating the milk to 190f for 30 mins in a pot and allowing to cool to 110f before seeding with bacteria. No need to strain with cheesecloth after incubation, just pour out off the top if desired. 12hrs incubation seems to work best for me. Going from frozen definitely needs 12hr as the bacteria will be slower starting than unfrozen source. You can get away with merely some scrapings off a yogurt ice cube as sufficient for seeding. Seems it can keep for a lot longer than 6 months in freezer fwiw; my freezeback is probably over two years old and still just as viable.