I would stay stick with stage one until atleast 6 months I started my son early on foods but I stayed on stage one cause of the texture

My baby started baby foods early too, most babies start at 6m but the only problem I had with 2nd foods at around 4m was that some of the foods were hard for him to digest. He would cry bad after some of the more complex foods. 2nd foods are fine for a 4m tho. You could also mix baby cereal with the 1st foods to make it thicker

i dont think i personally would but you should ask her doctor what she thinks