My ped also said it was better to have it on. He recommended I do a "test patch" to start with a while before she needed it, just to make sure there's no reaction. He also was very adamant that she get a bath in the evening every day that she gets it put on. He said to always keep the feet covered when you're going to be out all day, because some of the worst sunburns he's seen were on baby toes. It's an area often overlooked while putting on sunscreen, and most babies are barefoot a lot, and the sun hits their little toes. A lightweight cotton sleeper or other lightweight long sleeve and footed outfit and a wide brim hat could get you through the day without being sweltering for baby, and then you'd just have to put a little sunscreen on the face. Remember too, when putting sunscreen on the face, that the stick variety is better to use, because the lotion can run into baby's eyes if he/she does start to sweat, and that will sting.