I would recommend reading "Letters from a Stoic" or "Meditations" (which you have listed) rather than "Discourses of Epictetus". The former two are a more enjoyable read than the latter (imo), but they all cover the main tenents of stoic philosophy.

You really have to be discriminating with your choice of reading material, as you can waste a lot of time on books that won't add much to your life. Quality over quantity.