When my son was 6 months (now going on 8 months) he would wake up just like that. He would just scream until he got out of his bed. We would give into him cause we hated to see him cry. He finally realized that he was doing that because he was cutting two teeth. Poor guy! He has his two bottom teeth now and he no longer wakes up like that. He did that for awhile though, boy it was rough! I feel your pain! There were many mornings I looked at him wondering how he was awake on that amount of sleep and I was about to pass out. We also leave music on for him. It's by no means calming music but it's just what he got use to. It's the Mickey Mouse Clubhouse cd.
I have no clue how he sleeps through it, but he knows it's bedtime when he hears Mickeys voice in the bedroom. LOL Just as much as you can stick to your routine, even on holidays and weekends. Sometimes it's hard to do. My son gets bath around 8:00 then plays and eats and is in bed by 9-9:30. Sometimes if he is really fighting sleep we take him on a short drive. Works every time! Good luck!