Thanks for sharing, and yes: date changes on everything except the first segment is fine (as per rules anyway) at any point. The wording is:
Prior to departure: a. Changes are permitted provided ticketed points remain the same. If the first flight coupon is being changed, and the fare level has increased since ticket issuance, the difference between the old and new fare will be charged. If the fare level has decreased since ticket issuance, no refund will apply.