If you can, buy a high quality suppressor, if not, learn to make your own. Trust me when I say it is EASY and legal to do so as long as you do the appropriate paperwork. In SHTF, you can do whatever you want so whatever.
Reason being is that a suppressor will hide where you are shooting from. It does not make your gun silent, there will still be a bang if shooting supersonic ammo, but the sound of the shot will be nearly hidden from a target, potentially sounding like it is above or in the opposite direction from the shooter.
Yes it has already started. One side is fighting it, physically and through subversion, and the Right is not fighting at all other than meme's. If there is no blue wave, expect the Liberals and Leftists to go full retard and things will likely get violent.
They're not looking to have opposite sides line up and start shooting. Get that out of your head. It will be targeted assassinations, hit and run, and bombings. The biggest took used will be intimidation and mob violence - areas the Left has already shown to be cheap, easy, useful, and for them available now. (Its also why they want guns banned so bad)
Is it unaviodable? No. If the left wins and gets their way, they'll go away. If not, then yes, it is GOING to happen. They and their agenda can't afford to allow Trump and Republicans any further erosion to the Leftist agenda, because Trump has been overwhelmingly good for the US, both domestically and foreign policy wise, and they want to stop that by any means possible.
When? Depends. Is there winter where you live? I'm talking ACTUAL winter, not that milquetoast shit the southern US calls winter. Like 40 below windchills and feet of snow. If you have that, then there aren't going to be much outside assassinations, intimidation, vandalism, etc. In places where you dont have winter, yeah, things could get sporty occasionally.
Keep your powder dry.