I wouldn't fret over it. North-bound traffic on Sunday afternoons binds up shortly before Braves stadium, moves slowly through the City, and then frees up after I-85 and I-75 split. It could be worse if there's road construction inside I-285, but the signs will warn you as you approach Atlanta and then you can loop around the city. Incidentally, I regularly go around the city on I-285 not because of the traffic, but because all trucks (except for local traffic) must route around the city, and my personal driving style is to sit comfortably behind a sensibly driven 18-wheeler, relax, and take my time. It takes me a few extra minutes, but it does wonders for my disposition. YMMV.