Army Enlisted To Warrant Officer

So I'm going to enlist but I'm weighing my options between each branch. The only way I'd join the Army is if I would end up becoming a Warrant Officer (flight). Obviously that's not something I can get guaranteed to me so I'm wondering the chances of someone who enlisted to become a Warrant Officer? Does MOS matter when it comes to becoming a flight Warrant Officer (say I went in as an aircraft mechanic?) What are the realistic chances of actually becoming a Warrant Officer and how long I should expect it to take?