So long as a lotion is gentle and made with safe ingredients, you can apply it to your baby's skin whenever and wherever the skin is dry.
Keep in mind that less is more and most babies don't need lotion, to begin with. If you decide to use lotion on your baby, you may want to consider applying it after bathtime to maximize the skin's ability to retain the moisture, according to Solomonian.
If your baby's skin is consistently dry or irritated and the lotion you're using isn't easing the discomfort, she recommends scheduling a visit with your pediatrician.