If you look at my picture or the video, the PI ships were immediately in range of the lasers, which still needed a recharge. They were no in range of the energy missiles, but those still needed their cooldown.
as i said - dunno
In my tests, the unity ship warps in and a few fire immediately while other turrets (of the same type) took longer to hit the same target …
Is it 100% certain that all turrets were in range?
Yeah, well and truly, Extended Taychon cannons on the tutorial map - overkill in the extreme 
Several of them were, as denoted by the white “target acquired” square on the weapon grid.