In non-retail setting, I would say apply once you take your licensing exam and find out you passed and just waiting for the actual license (It can very from state to state, but generally you wait 1-4 weeks). I applied really early when I was graduating, and the response was always we are looking to hire someone right away, and a lot of employers don't want to hire someone and then wait 2-3 months if s/he failed the NAPLEX or because they never took it yet.