Welcome to world of working dogs!
We have an Australian Cattle Dog (blue heeler) and he's 3. While he's mellowed out in the past year, he very much requires exercise. He tends to be a bum during the day and is happiest with a 20-30 minute run in the morning and either a walk to the dog park or a looooooooong walk/run in the evenings. When we have busy weeks and he's couped up, you can definitely see it on his face.
Working/herding dogs tend to do very well with a "job". Some like to herd things (balls, toys, cats, children), some like Kongs (where you have a toy with a piece of food inside that you maneuver out). Dax prefers his Buster Cube. It's a big plastic cube that when pushed around the room dispenses kibble.
The thing to keep in mind is that they need to work their minds as much as their bodies.
I think 2 walks a day is adequate with maybe hikes and trips to the park thrown in for good measure. Also, since it's coming up on summer and Aussies tend to have thick coats, I would bet that your dog is going to be like mine in the sense that he/she wants to "work" in the mornings or when it cools off at night
Congrats, though!
ETA: One more thing. If they really aren't getting enough exercise, you'll know. We were curious about the same thing, but we quickly learned that not exercising him enough resulted in some pretty clear signals- a destroyed house, anxious-ness, or even just the look on their face