Then according to the time of the year, add yogurt to it. If it is summer, add about 1-1½ tsp. of yogurt and if winter then ¼ - ½ tsp. is enough. Now, stir the yogurt into the milk and let it set for about 8 - 10 hours. Depending on the time of the year, the yogurt will either set fast (summer, 4-5 hours) or will take a little time (winter 8-10 hours).