Yeah of course! It's generally not recommend in really young babies, because a key element is the ability for them to sit up so as not to choke, but if at 5 months she has sturdy head control and can sit with your support (or in the high chair either way) there is not too much reason not to. Part of BLS is following when your bab y is ready, if she is ready at five months, go for it, but in some cases you may need to backtrack to mashed textures! Banana is a great one to start with!