Answer:
The metrics and dimensions I should include in a custom report to deermine the day and time when users are most likely to complete a purchse after I sent them an email promotion providing a discount to users with a birthday in the month of September. are:
Day of Week, Hour, eCommerce Convertion rate, sessions.
Step-by-step explanation:
The reasons behind these answers are two: The first one is that I need to write a record of the people to follow my call in the e-mail. So that record should include day of week, as well as hour to study their behavior. Also, the e-commerce conversion rate to analyze the effectiveness of the e-mail promotion and the sessions to find out how much people entered at the same time.