Starting early each day is the way to go I reckon. Sunrise is @ 5:18, sunset at 21:15, so early starts will make better use of the daylight. And as the forecast is starting to look scorchio again, will give you more miles at the coolest part of the day.
Day 1 is 300k, with a similar amount of climbing to the Elenydd. 16-17hrs to get to Llanwrtyd before 1 will give time for a couple of hours kip before heading out again at 5am latest.
Day 2 is 320k, the amount of climbing is similar but as everyone will tell you, it's not a quick ride on this leg, and the 2018 version is tougher by some way than the 2014 route. The first 240k particularly - once you get to Laugharne the 80k back to Llanwrtyd are definitely easier. Whatever you do on Day 1 you can add an hour for the extra 20k, another hour because you're tired and another hour because it's just a slow part of the route. So leaving at 5am will get you back for midnight-1am again with time for another few hours kip.
Day 3 is another 320k to Vyrnwy. An early start will see you with a decent chance of making Pete's Eats (230k), which I'd definitely be wanting to do, as the 90k from there to Vyrnwy is hard - 3 big mountain climbs, remote country, and almost certainly in the dark - you really want some time in hand leaving Llanberis. Once you get past Aberystwyth though it's an easy run up the coast so you can get some time back on the way to Llanberis.
From Vyrnwy it's an easy run back to the finish once you've got the initial climb away from the lake done with. There'll be plenty of sleeping space at Vyrnwy and Danial runs a great control, so get another couple of hours kip and leave at first light again to do the last bit in daylight and finish at a civilised hour (which I definitely will appreciate not having to stay up all night).
