The important thing here is to make sure your boss is aware of your intentions for a promotion. The way to do that is to tell him. Then, in that very same conversation, ask him for any feedback he might have on areas where you could improve. This is critical because it lets him know that you are motivated to improve and will do whatever it takes to move up. Four months is not a lot of time to be working at one place. It would be unusual for an employee at any company to get promoted so fast. That’s not to say it can’t happen, but I’d encourage you to let go of the notion that you need a promotion right away. Instead, focus on being a quality employee every minute of every day and trust that good things will happen when they need to happen. Management usually wants to know that an employee plans on sticking around for a while before promoting them. The only way to demonstrate that is to stick around for a while. Hope that helps.