I don't know anything specific about these super saver fares, but it seems very odd to me that they'd be having a sale during their peak travel time. That's normally when they increase prices, not decrease them. If it was me, I certainly would not wait to book any trips during that period. In the past, I've always booked my summer travel as early as possible, though it's normally with OZ, not KE. When I've had to wait in the past due to my schedule not being fixed until late, I had to pay some very expensive fares, and in one case had to book a business class ticket instead of economy.

Now if for some reason a particular destination isn't selling well, then I could see perhaps they'd have a sale for that particular route, but I would think CEB would be very popular with vacationers. More so than Vietnam.

The Philippines seems to be a difficult route for me. There are times when it seems booked solid for a month or more at a time. I've often bought my tickets 8 months in advance or more, especially during summer or December/January. If I know my plan and think it's fairly certain it's fixed, I never wait in hopes that it will open up more later. I would book my ticket ASAP. Waiting in hopes of it going on sale could potentially save you a couple hundred dollars. But the opposite is much more likely I'd think and you could find yourself spending many hundreds extra, or even worse not being able to find any route unless some odd route via another country.