Ideally your healthy newborn should be around 2-3 months old before being exposed to the recycled air, germs and the large number of people on flight.
However for most healthy babies, 2-3 weeks is a reasonable time frame in case you cannot wait.
Get her examined by your pediatrician, including the ears, and carry medicines like Crocin (Acetaminophen) for any fever/ pain/ irritability, and you should be good to go !
Many parents worry that the changes in air pressure that happen when you fly can harm their baby's ears. It's true that "popping ears" during takeoff and landing can be a bit painful for some infants, but it won't cause any lasting damage. Your baby will feel more comfortable if he has something to suck on during takeoff and landing, so you may want to breastfeed or give him a bottle or pacifier. You can give him some infant pain reliever (such as acetaminophen) if his ears really seem to bother him.
Get more tips for traveling with babies here