Research suggests people who have very recently experienced a trauma may not be ready to recount it in detail, and this may cause more harm than good. If you're concerned, or thinking of starting therapeutic writing, consider conferring with a psychological professional. You can also try starting, and if it doesn't feel right, stop. Or try writing for short periods and taking breaks.
Often to heal, people feel worse before they feel better, because a lot of the things they've been avoiding resurface. But bringing things to the surface can bring a new perspective, so memories don't feel so heavy. You know what is right for you, and what isn't. Take your time.