The repeal should have been in the works from the day it was put into law.
There is certainly enough about it that is irregular and illicit for them to have been challenging it from the day it was enacted.
The repeal has been in the works since the Republicans took control of the House. So far the multiple repeal bills passed by the House have died in the Senate. I suspect early next year the Congress will send Obama a repeal bill which he will promptly veto.