It really depends on what you think you might enjoy and what she shows an aptitude for. Whatever you do, you'll be doing it together, so pick some things that interest YOU, and see how she does. Does she like to swim? Try dock diving. Is she agile and athletic? Agility might be the perfect sport. Does she like to retrieve? Flyball is tons of fun! She's probably old enough to take nosework classes right now. There's also lure coursing and sprint racing.
No matter what that turns out to be (and it doesn't have to be just one thing, it could be several), you'll need a foundation of basic obedience, so start working on that now. A lot might depend on the resources near you too. What kind of training facilities are in your area, and what sort of classes do they have?
We are almost done with the advanced basic training now, I'm in Dallas so there are a lot of options near me, its just narrowing it down. She has shown an aptitude with her nose.
I agree with Cassidy'sMom: Go with what she shows she likes or seems to be good at.
For what it's worth, I didn't do anything but obedience with my dog until she was nearly 2. She had pano, so that was part of it, but the more I got into obedience (we've been training continuously since she was about 10 weeks old), the more I saw it as necessary life skills and we focused on training and getting our first title. We've eased way off on obedience now; we still attend class weekly, but any effort I have time to put in is dedicated to Nosework, which we also do weekly.
The advantage of waiting was that I had extra time to get to know my dog as she grew up, and I observed her natural behaviors and tried to extrapolate what she might do well. I noted that she doesn't enjoy most agility-related activities. We may still try an intro agility class just to build her confidence with jumps, but I don't expect her to excel or even to have fun. I wouldn't continue that with her unless she surprises me and likes it.
We tried herding, and I had a blast, but I don't think that will be a strength for her; she kept trying to cut one of the poor ewes out of the flock, which is not at all the object of the game.
One of the most consistent things she has always done is keep her nose to the ground whenever she's allowed. She loves "finding" games and would live with her nose to the ground if I let her. So scent-related activities it is. I put her in an intro Nosework class and she took right to it. She loves it. And it was one of the most fun moments of dog ownership to put my dog in a search area for the very first time and watch her just light up and switch on like she never had before. If you know your dog - you'll just know when something is a fit. I knew after that first night we'd continue in Nosework for fun even if we don't compete (but I plan to try titling her if she can pass her ORT).
Look for training clubs or working ranches in your area that do fun days - you can "sample" activities for an afternoon and get a sense of how you and your dog would like them. That's how I was able to try herding and how I'll try barn hunt.