Final answer:
A licensee can engage in business as soon as their license is officially reactivated, which requires meeting specific conditions set by the licensing authority.
Step-by-step explanation:
A licensee can engage in business activities once their license has been officially reactivated. The exact moment they can commence business will be dependent on the regulations and rules set forth by the licensing authority which could be a state or professional board. Typically, the reactivation process involves completing any required continuing education, paying necessary fees, and possibly submitting to a background check. Once all conditions have been met and the license is reactivated, the licensee will receive a notification, and they are usually free to engage in business activities from that point on.