You are certainly going to get ALOT of differing advice on this one. So, just my 2 cents. I agree with Jamie, I don't believe in CIO and there is no need for any child to cry themselves to sleep. We are parents 24/7 and if your child is crying in the middle of the night, it's because they need something, even if it's just a hug. Good for you for listening to your gut and your son.
Neither one of my kids slept more than 4-5 hours at a stretch until they were over a year. For my son, it was 14-15 months. For my daughter, it was almost 2 years. One thing that I remember reading was to not do any more stimulation than absolutely necessary. No lights (or as little as possible), no talking, no diaper changes (although, 5 months might be too early for this). No diaper, because if he were sleeping all night, you wouldn't wake him to change him. But, obviously, if he is soaked, change him. I think that I started this kind of routine around 10 or so months with mine.
Again, Jaime is right, it really doesn't last forever. Even if sometimes it feels like it. lol And, yes again, on the sleep when he sleeps. Good luck