Final answer:
The closing waiting period for a mortgage begins on the third business day after the Closing Disclosure is mailed, as mandated by the Truth in Lending Act.
Step-by-step explanation:
When XYZ Mortgage Company mails a Closing Disclosure to a consumer, the waiting period before closing officially begins the third business day after the Closing Disclosure is mailed. This is a legally required waiting period, which provides the consumer with adequate time to review the terms of their mortgage, which often spans over 15 to 30 years, and assess the credit implications as discussed in the relevant section. This rule is part of the consumer protection measures under the Truth in Lending Act (TILA), as implemented by the Consumer Financial Protection Bureau's (CFPB) TILA-RESPA Integrated Disclosure (TRID) rules.