under out current situation, what is the optimal timeframe to act?

assuming the grid goes down, which seems to be a pretty realistic threat right now, what do y'all thing as far as the timeframe to act is?

it's my understanding that as soon as people realize what's happening, a large amount of people would head for the hills and roadways in large cities would get completely plugged up. I already experience gridlock in rush hour traffic anyways, so I can't imagine what it would be like if SHTF.

My current plan is to wait out the first day and try and get some information, get my people together and the truck loaded, and then head out late that night. yes, I do have a place to go. I am currently living in an apartment that would not be safe under any sort of rioting/looting conditions. I am torn between my plan A and B; leaving immediately, sticking to backroads and mountain roads. thoughts?