Can a ninja explain this to me

[Greywolfamakir]

I said I like it, not that I prefer it. I like opening with suiton.

If you wanna know the actual benefits of suiton after DE/AE its that suiton gets fully buffed by B4B/IR/Pot(Not sure if Foe is on target if suiton is first attack). Not that I'd weigh it over opening with suiton, but you asked.

Suiton should be used asap, but TA should be used after 3-5 GCDs because DPS jobs need around 3-5 GCDs of preparation during opener, I mean:
MNK; 5 GCDs for full buffed. (3xGS + DK + TW)
DRG; 3 GCDs for full buffed (Heavy Trust + Disembowel)
BLM; 3 GCDs preparation for Fire IV spam.
SMN: More than 5 GCDs for Trance.
BRD; 3 GCDs preparation (Straigh Shot + 2xDoTs)
MCH; 3 GCDs preparation for Wildfire opener (Hot Shot + Lead Shot + Split Shot)
WAR: 3 GCDs for full buffed (Maim + Storm Eye)

There is no reason for use TA before 3-4 GCDs.