Aperture bracketing with waiting time for Speedlites

[Xenith]

Hi,

in some specific cases I have my 7D or 5D MKIII set up with aperture bracketing (+-2EV, ISO shifting half).

With Yongnuo YN-E3-RT Flash trigger unfortunately only the first and sometimes the third frame gets flash exposure as the camera is not waiting for the flashes to be ready.

I thought I might write a script that first waits for the flashes, then sets aperture and takes the photo. Is there a possibility to get the necessary information? Or is there even already a script that does it?

Thanks in advance!