If you BUY a ticket before the 15-Apr changes, then you are grandfathered. As long as the 1st segment has NO changes, even date/time. Changing the 1st segment is akin to getting a brand new ticket. Last year, I bought an ex-CPT ticket before the fare increase. I randomly chose a date for the 1st segment. All of the experts at the AA RTW desk told me, don't change that 1st segment or it goes to tariffs for re-pricing. So, if you want to secure the rules as stated now, you must buy the ticket before 15-Apr. I am doing that, yet my 1st segment is not until mid-Oct.