Simple answer: if any of the colleges to which are applying requires the writing section, then you must take it. If none requires it, you are fine not taking it.
As to timeliness, the ACT writing section is usually graded for almost everyone by no later than a week to two weeks after test scores are intially released. However, the September 2015 test seems to be having more issues than usual because many still do not have their writing scores. Do not know why there is an unusual delay for that test. In any event, check the colleges to which you are applying for last test accepted for determining admission. Most with Jan application deadlines accept through the Dec test and many even accept the Jan SAT test, i.e., the test scores can arrive after the application deadline.