I have to be at SFO on a Friday night, around 6-7PM, heading in from quite a bit north on the 101 and back out the same way.
What is the best way to do that and not want to shoot myself? Traffic into town begins how early? Traffic out of town is insane how late?
Any tips or ideas to minimize the misery?
Are you coming down from the East Bay or Marin? Both are pretty brutal, but there are more options from the East Bay. If you are coming from Marin you should head down 19th Avenue to 280 then take 380 to the airport so you can avoid the hell that is downtown SF/101 south. From the East Bay, I would check google maps and see which suggested route shows as the quickest at the time you’re traveling. It might make sense to come down 80 or 580 and cut over on the San Mateo bridge if traffic through SF is too brutal…
On Fridays in particular, the afternoon commute starts insanely early - 3:00 ish. The good news is it’s a bit of a reverse commute with lots of young tech workers headed north from jobs in Silicon Valley to homes in SF so southbound will be a tiny bit less crazy.
For the return trip, I’d be inclined to get a bite to eat somewhere near the airport and let the traffic die down a bit, particularly if you get out of the airport closer to 6 than 7. Waiting until 7:30 - 8pm might make you slightly less miserable. Good luck.
I recommend the Waze app too for help in avoiding traffic nightmares.
From 101 we are headed south over the bridge
Google maps work like magic in Bay Area (duh!) - Waze data is plugged in there, and GM traffic reports are very accurate. If GM says take a side road, take the side road. 
Take the BART, then you don’t have to worry about traffic.
I second, take BART for the last bit.
IMMEDIATELY after you go over the Golden Gate, be in the right lane and turn right at the first opportunity. Looks like you are going into a parking lot. Turn right on Lincoln Blvd. Go past the Legion of Honor and through the golf course and (I think the name changes from Lincoln to something else, but as long as you pass Legion of Honor you are on the right road). turn right on Clement. Follow Clement west bound past Veterans Hospital and at end of road make a left, then immediately a right at the light. Now you will go past Cliff House and be on the Great Highway. Set your cruise for 35MPH because the lights are sync’d and you will cruise down to Skyline and turn right. Skyline makes a funny hook where you go on highway 1 the wrong way to get on 280 south bound.
Then you stay of 280 to 380 having avoided most of the traffic. DO NOT be TEMPTED to take 19th Ave.
You can catch the Daly City BART off 280.
If you drive all the way to the airport, then just take 101 North back. By 9 the traffic will be calmer.
Thank you, @esobay , that was perfect!