The first thing that should be done before allowing users to connect personal devices to the corporate network is to implement an acceptable use policy. An acceptable use policy is a document that defines the rules and guidelines for using personal devices on the corporate network, such as security requirements, access rights, responsibilities, and consequences. An acceptable use policy can help to protect the organization from potential risks such as data leakage, malware infection, or legal liability. The other options are not as important as implementing an acceptable use policy, as they do not establish the boundaries and expectations for using personal devices on the corporate network. References: CISA Review Manual, 27th Edition, page 318