Arena speed question

I am curious as to how much more speed is required to "ensure" a character will go before another. Specifically, I am running HK (L), 88, 86, JE, and Poggle. Respective speeds are 127(30), 123(2), 119, 162(15), and 142. I think it would be cool to have HK go first to apply his debuffs so 88 goes next with more damage. However, even with 4 less speed, my 88 goes first every time after JE turn meter boost. I know the speed is supposed to be somewhat random, so at what speed difference will my HK consistently go before my 88 after turn meter boost?

There used to be a huge thread on how arena speed worked but I couldn't find it. Anyways, besides the whole speed thing, is the HK going first strategy the best choice? Or is there a reason you'd want differently? Also looking to switch out Poggle with Nebit soon to see how it works.

Thanks!