It might be best to cut yourself a little slack right from the start of March, which is very likely to maintain the rather staid vibe of the previous month. If you allow yourself a little leeway in whatever restrictions or limits you may have imposed on yourself, then you're far less likely to go overboard by the 11th. Your areas of potential weakness or slippage are the usual: food, drink and cash!
Sagittarians have quite a zany, fun side to their natures; they can also be deeply passionate. After the 20th you'll be able to tap into that part of your personality far more easily if you feel that all the sensible stuff is under control. Don't let work or domestic matters get brushed aside. Do address these things as and when they crop up and you'll be able to enjoy a rare sense of freedom!