If you're just starting to wonder, chances are your pup is not ready yet. Off-leash training requires a lot of effort and a pup that has an easy and fun time choosing you over all distractions around them.
Most pups are ready to begin off-leash training around 4-5 months. By then, you want to make sure that you've tested the waters in safe and controlled environments, where you can easily redirect your pup should he get distracted and lose focus in the exercise.
Always add to the mix a long leash for extra safety and to ensure that when you call or need your pup to come to you that it happens, as you use that leash to more easily guide and encourage your pup to choose to come to you, in a fun way that they'll want to repeat no matter what.