Depends on the registrar and how you intend to deliver the domain.
- Some registrars might allow a transfer out at 30 to 40 days.
- Others will make you wait the full 60 days.
- Some even require prior authorization from the registry before a transfer can happen after 60 days.
With the above in mind, many (Not all) will allow you to "Push" a domain to another account within the same registrar within 48 hours of registering the domain. In that instance, you just have to make sure the buyer has an account at the same registrar, so you can push it to their account and avoid the 60 day 3rd party transfer lock.
Be sure to research your registrar to make sure they allow account Pushes.