Once you send the job application letter be it using Sample Job Application Letters for Internship template or some other template, it is imperative that you may have to follow it up. However, you need to find the right time to do this. An early follow up would portray you as desperate while a late follow up will lead the company to consider you as callous. The best thing is to wait for a week after sending the job application letter. In case you do not hear anything from the company and you are really interested in the job, go ahead and send them a follow up mail or letter.