During execution you want to involve the business lead before users, but the business lead is engaged in another large project and cannot attend the meeting. What should you do first?

The best first step is to summarize the changes and potential user impact in an email to the business lead. This respects their busy schedule by providing key information concisely, allowing them to review it at their convenience and understand the situation before further engagement. It also creates a documented record of communication. Asking a delegate might not provide the same level of authority or insight as direct communication with the lead. Adjusting the project completion date is a significant scope change and premature without first attempting to inform the lead. Adding resources is a reactive measure and doesn't address the immediate need for communication and stakeholder engagement.