At 90°F, remove the pot from the burner and slowly add your rennet (which you prepared in step one) to the milk. Stir in a top to bottom motion for approx. 30 seconds, then stop.
Cover the pot and leave undisturbed for 5 minutes.
Check the curd after 5 minutes, it should look like custard, with a clear separation between the curds and whey. If the curd is too soft or the whey is milky, let it set longer, up to 30 more minutes.