Look
here for the Oktoberfest schedule. But don't worry about it too much. The terrst from the city only know a couple of ways to get there and there are actually several. Helen itself will be a mass of folks but you'll be fine once you get out of town a bit.
To get there from Texas without slabbing through the metro crawl, just deviate to the north. Find your way to Chattanooga, more or less, then you can either go ahead and veer south into GA or head east across eastern TN/western NC. The TN/NC option would put you on some great roads including the Cherohala if you like or you can just follow US 74/64 to the east for a while. Its a 4 lane divided job in places but a very scenic trip also. Watch the speedo as NC is known to patrol it kind of heavily at times. When you get to Murphy, NC watch for US 64 to split off to the right and follow it (take a left there for an entertaining detour back into the hills around Lake Hiawassee. Go till it deadends (ignore the gravel road warnings, trust me), turn left, go till that deadends (over the dam) and turn left again, go till that deadends and you're back at 64/74 about 8 or 9 miles from where you started). Follow 64 east till you get to hwy 175. Turn south. That road will become GA 75 (NOT I-75) when you cross the state line and will take you into Helen from the north.
Another option from the Chattanooga area is to take I-75 south into GA and then turn off on US 76 East at Dalton. When you get to Chatsworth, watch for GA 52 to split off to the east (left). This is a really nice ride across Fort Mountain. Follow it all the way to Ellijay and then get on 515/5/76/Zell Miller Mountain Parkway etc headed north. Follow the signs from there to stay on US 76 until you get to Hiawassee, GA and watch for the aforementioned GA 75 south which, as above, will take you into Helen.
Except for the little jaunt across Fort Mountain, the second route is much more boring slabbiness than the first but is probably a bit quicker. Either option will keep you well clear of the metro area. Traffic through Chattanooga can be a bit heavy if you hit it at rush hour but is not even in the same league as Atlanta.
On the other hand, if you just want to get there quick, don't be too afraid to blow right through Atlanta. If you hit it outside of rush hour (rush hour is 6-9 am and 3-7 pm mostly), it isn't that bad. Be patient, be very very very alert, know where you're going before you get there so you aren't caught in the wrong lane and you'll get through it pretty painlessly. I-285 (the perimeter loop) can be quicker than going into the heart on I-20 and then north out of the city on 85 but is also much more likely to grind to a total halt due to some snafu. The through town route is always slower but less subject to crash blockage. But if you don't have a good bit of urban expressway riding experience, it is NOT a good place to learn. Beware the 75-85 split headed north out of town. Its backwards. I-75, which leaves Atlanta headed northwest, goes to the right and I-85, which heads northeast, goes to the left. Don't ask me why. I don't know. I think it was a joke the DOT decided to play on out of towners.
My $.02. Well, OK maybe it was $.52 but I've lived here a long time and have a lot of opinions about it.
Enjoy north Georgia. Ride the 129/180/60/19 squid loop if you must - great roads - but watch out for the Mitty's on their GSXRRZXRS's and also the constabulary chasing them.