You are right. When I was initially looking at it, it didn't seem like I was getting the last couple skills under the HE/B4B timers if I popped them first prior to LS, so I was comparing the difference in gained potency from Wildfire if I delayed the cast till after LS.
One of the issues I was running into with excess latency, was not fitting the skills into the Buff timers and, my first Slug Shot not registering under Wildfire. Which I thought to alleviate both with swapping out of Gauss Barrel to have Wildfire Initialize quicker between the GCD and to be able to cast my buffs during the first couple GCD while not under the effect of GB. But, for some reason the AA Damage does not have as big of an impact on Wildfire, although calculated higher potency for AA + Split and AA + Slug. (and it gets very clunky swapping GB mid Burst)
So here's what I ended up doing, which is pretty well the same as the Double GR Opener.
Hypercharge, BFB, HE, RS, Tank pulls the boss, Gauss Round
Hot Shot | Pot
Lead Shot | Reload/Wildfire (this lets me get Wildfire Credit for both the first Split and Slug Shots, where as if I used Wildfire on the next Slug, it wouldn't register before Slug goes off due to it being instant cast)
Split | Quick Reload
Slug | Ricochet
Split | Reassemble/Rapid Fire
Clean | Blank
Slug | Head Graze
Split|
Clean | Gauss Round
Wildfire goes off