Chicago to Georgia help
 

I just found out that i'm driving a 16 foot box truck, fully loaded, from the Wrigley Field area to a town called Flowery Branch, Georgia tomorrow, Thursday March 18th, and i'm supposed to leave around 6 or 7pm.
My google maps is telling me to take I-65 all the way to Nashville then take route 24 until that turns into route 75, which will take me all the way to route 285, just north of Atlanta.
From there it turns into route 85 which will take me northeast up to Flowery Branch. Now there's 2 small issues.
#1. I've never drove through the mountains, not sure what to expect.
#2. Would I save time taking route 20 east, before heading into Atlanta, and take that through Canton and Cumming?
Lastly, i'm used to driving from Chicago to NY on i-80 so this is going to be different, but any tips or suggestions would be GREATLY appreciated. I'm just looking for the best route so i can get there quickly and safely.
I'm supposed to be in Flowery Branch sometime around 9-10am Friday morning but since this is a last minute thing, and my patience is already thin, whatever.
I planned on going out and joining my fellow Irishmen for a night of drinks tonight but that got cancelled because i take driving seriously and care for others...alcohol can wait.
Thank you in advance.

Count on 12.5 to 13 hours driving time. With a fully loaded box truck the gas bill will go over $100. Hope that your truck is well maintained and has good brakes. Depending on the load, you may be slow going up hills. If you are on a long downhill, downshift to save on brakes To avoid Nashville you could take US 231 south from Bowling Green to save some miles. If you could start earlier, I would. Take a nap this afternoon. Hope you don't have to load the truck yourself before driving.

Thanks for that info. I just woke up and plan on a 12-13 hour trip. The truck is only a year old and i'll be careful but i'm still wondering about that shortcut of taking route 20 east instead of continuing going south towards Atlanta.
I'll take a look at 231, so thanks for that. I'm going to be leaving here in about 3-4 hours and when i get back, i'll reply with which route i took so maybe someone in the future can take a look and get some ideas.

I'd give it a try. It looks like an adequate secondary road (not interstate).

When you get a chance, can you give us a trip report?

"#2. Would I save time taking route 20 east, before heading into Atlanta, and take that through Canton and Cumming?"

You may not save time but Highway 20 is a main E/W corridor. I hope you are having a good drive.