Another vote for doing what works for getting the words on the page as expeditiously as possible regardless of which approach you adopt. There is no right or wrong way. Also, do not be discouraged if your first draft is a steaming pile. Bad writing, as opposed to no writing, can be fixed.
Personally, I think I would try to have a good idea in mind of the main story threads and, particularly, how the story ends, before I committed to starting, but that may not work for a writer, who is a dyed in the wool discovery writer/pantser. My outlines go all to hell after my first 10K words, so I have stopped lavishing too much energy on them.