Should I open an LLC and file for Trader Tax Status with MTM?

I'm an active trader, i fit the criteria for trader tax status.

if i elect for this, along with mark to market, is it generally beneficial?

Also, should I open an LLC?

I would like to trade as TTS and MTM for the entirety of 2018, if I form a new LLC now (December 4, 2017) would i be able to elect MTM treatment for all of 2018?

I was under the impression that I'd have to attach a statement on my 2017 taxes indicating that for 2018 i'd like to change my tax accounting to MTM.

But, then I read somewhere that if you open a new LLC, you can choose MTM accounting from the beginning.