How many days do I wait until I contact the company I interviewed with, to see if they've made a decision?

I would usually wait until they called me in this situation. If it has already been 3 days however, it might not be a bad idea to call just to keep your name on their mind. As long as you don't come across as pushy, needy, or annoying, they may view it positively as a sign that you are interested in being part of their team and not afraid to follow up. Go ahead and give them a call. What do you have to lose?

it used to be 5-7 work days.