I usually email them 1.5 weeks later if applied online.
I will call them in two weeks if I mail my resume.
If apply in person, I call in one week.
Not sure if this is protocol, but is what I have done.
I think a follow-up after 2 weeks is appropriate. If you receive a positive response, you may send out reminders at 2-3 week intervals. If you receive a negative or no response from the follow-up, move on to another company.