It's a good question.
I usually use cold water, and start with a cold canner for the first batch. Then if I go to a second batch I pour the boiling water into the room temperature jars, put in the lids, wait for the first batch to be done. The hot jars cool somewhat. Then after the canner is empty, still having very hot water from the first batch, I add cold water into the canner until it is just warm and dip out any extra water. You want the temperature in the water to be similar to the jars. Then I can put the second batch in the canner and begin.
I don't ever remember the jars cracking when adding boiling water to room temperature jars.