You're assuming the employer will contact you back. There is no set policy for this, it would depend on the company.
Molly recommends the following next steps:
- Don't ever wait for someone to call you. Show that you're "hungry" for the experience. Give them 3-5 days and call in to see if you can 1) Talk to someone regarding your intern application, 2) Where it is in the process and 3) Is there anything more you could provide for them.