I proof my dough in a warm oven. I turn my oven on to warm (170 degrees); once hot, I cut it off before placing my dough in. This technique is a great way to proof bread in the winter or when it’s cold out. Another technique is to place your bread inside on the top rack, fill a pan with boiling water on the bottom rack, and close the oven door. The residual heat will keep the oven warm.