When can I stop putting diaper rash cream at night? Does it only stop when they are potty trained?

My prevention method is to use cotton with water (or just rinse with water when LO older) to clean instead of using wipes. Make sure the faeces are cleaned away completely. Both urine and s*** can cause rashes. No rashes no need cream. I use sebamed baby cream instead of diaper cream as I find it difficult to clean. After cleaning, air dry completely before putting new diaper. It helps a lot to keep dampness and discomfort away and reduce rashes. Two cents' worth from my personal experience.