The timeline if i recall correctly is:
Escapes (probably so that he can take a look at Hope)
Takes a look at Hope which makes Cyclops abort his current mission to rescue her
Wrecks the entire extinction team
Allows himself to get caught for keikaku
Hacked Danger so that he can have digital tea and crumpets while engaging in S&M play with Danger
Phoenix shows up.
Gives Danger a security patch and leaves to separate the lights while explaining the plan for fun since noone is going to remember it.
It's possible I forgot him saying a specific line or two but for the most part him waiting for an avengers vs X-men battle doesn't fit into controllable variables of everything else in his plan nor make sense as a thing for him to specifically wait for when he can teleport into their beds at night to rewire their brains thanks to not actually being in jail. The security there is lax enough that Transonic was able to hold Hope at gunpoint and he can teleport too. The step where he messes with the lights just plainly has a billion ways to take effect before anyone notices from what we've seen as his capabilities. The idea that he needed everyone that could stop him on that island to leave when everyone that can stop him leaves on a regular basis just feels really silly.
Heck. The avengers were even off planet for alot of the event since they went to space to stop Hala from being burned to a crisp and some other misc junk.
Then there's Gillen saying in an Iron Man interview shortly after the event that either side would have resulted in the phoenix burning everything.
All signs point to Unit being capable of carrying out his plan no matter what.