People that will be most willing to read the books you recommend are the ones that ask. When they come to you and ask, they are letting you know that they are ready. You can always offer, but that is all you can do. It is up to them to take it.
Also,
Don't judge where they are at in their life. They may need to be there to gain some experiences that they require in order to know their own love. It is all in its perfect timing.