When can I play the Mass Effect 3 DLCs if I've already beaten the game?

I want to get and play the Mass Effect 3 DLCs, but I've already beaten the game and don't want to do another playthrough just for the DLCs. Can I still play the DLCs?

If I recall, ME3 has a few auto-saves that it keeps, so I should have one right before the final mission(s) of the game? Could I simply use one of those for the DLCs, or are there certain points for each DLC where after that point, you can't activate them anymore?