Nothing has worked for us. DS is up at 5:45 on the button every single day. After the clocks changed, we got two days of 6:45 then right back to 5:45. It boggles my mind how precise he is. Anyway, I've tried everything (including posting here!) and nothing can get him to sleep in. The two things that save my sanity are that he goes to bed very early (6 pm) so I get time to myself then and I go to bed around 8 every night, though I wish I didn't have to. Also, he is a great napper and is a fan of alone time so he goes back to bed around 8 am for another hour or two. If I'm good, I go back to bed then too.
Try everything but you may just have to accept it and rearrange your schedule and just get used to it. Before we know it they'll be thirteen and we'll be complaining about how they sleep till 2 (sorry, not helpful at all!

).