I've been waiting to hear back from Human Resources concerning a job I applied for a couple months ago (March 17th). I received a letter informing me they've received all the materials needed for my application (April 9th). How do I know how long I should wait until I hear whether they are interested in interviewing me? Should I call and ask them to tell me when they plan to make a decision? I don't know how long I should expect to wait.