The brain is a complex organ, and every injury it sustains heals uniquely, based on the type of injury and severity. Therefore, there’s no standard window of time to wait before drinking after a concussion.
It’s best to avoid alcohol until all head injury symptoms have resolved and then consult your doctor for a final assessment. They can advise you if you should continue being extra-cautious or if you can begin to resume normal activities.
To be safe, when you start drinking again, you should do so gradually. Try not to exceed a safe amount, and track how you’re feeling when you drink. It’s possible for the effects of a brain injury to linger without noticeable symptoms.