I would not start running ads right out of the gate. You could show something funny while the pics load instead of ads.
I'm planning to replace the ads on the main page with incentive prompts to get people to add their own pics. Nothing mandatory, just something saying, "Hey - I bet your dog is cute too. It only takes 30 seconds to add them."
It was configured to end a match after one dog got 5 votes and won by two, a process that normally takes hours. It took less than a second with the HN traffic. My bad.