I think optimus will be absent for the majority the movie we may get a few scenes with him throughout the movie to see what happened with the creators but I think he wont return till right at the end. After they think they've beaten the bad guy. Optimus shows back up everyones all happy. hes back. they start running towards him to greet him like the trailer shows with bumblebee and Cade. Then optimus turns around and strikes them and im assuming a large battle follows and they realize oh shit this isnt optimus. Then unicron arrives and they all realize how wrong they were and whoever the bad guy was supposed to be was just a distraction by Unicron. And the Human bad guys are probably in on it to.

 

We see blue eyed Optimus too.

 

Thats why I said well get a few scenes with him to show what happened with the creators but for the most part optimus will not be in the movie till the very end imo.

 

No offense but i'm thinking the exact opposite. I think that he will be the main deal of this movie, how he goes to space, looks for the creators, maybe they kill him and left him to rot in space? Maybe Unicron finds him? Maybe Megatron finds him with the Knightship? Who knows.. But its for certain he will turn evil, maybe dark energon, or there will be another optimus, like nemesis prime.. Maybe built by Unicron or the Creators? I really, really hope this movie is about him since Bee is getting a solo movie after TLK. And TLK also focuses on optimuses and megatrons past, the primes and the quintessons

 

I dunno. That does raise the question of who's uncovering whatever it is that ties all the films together. I'd assume something that big would have something to do with the Creators, and it would be weird if the humans and/or other Autobots just happened to find it at the same time Optimus is searching for the Creators. I'm thinking he'll return early on and go on a quest to discover the ancient artifact, only for the discovery of it to trigger mental programming the Creators gave him, while he was in space.

 

I don't think Bee was running towards berserker Prime to welcome him back. Bee was out to stop him from doing whatever it was Prime was about to do.
If I remember all the leaks and fan pics right, whatever they are all standing on, surfaces in England. So maybe Roddy is there to help his broin arms, though I still think Hound knocks Prime off Bee (if Bee is unable to throw Prime off).
I'm leaning towards Prime showing up at the beginning of the last act of the movie. I think Team Autobot goes from fighting the Cons for energon, while alluding the TRF in the USA to having to treasure hunt for relics to save Earth (and Cybertron). They may think Prime is not coming back, and they take his words to protect their human friends to spark.
They somehow discover there is something headed towards them with the intention of destroying Earth. They look into Cybertronian lore and history for clues, which lead them to England. The Cons follow them there. The Bots come across a group of fellow Bots hiding out in England, and form an alliance. They all start searching for a relic or two that is said to be located in England. They find whatever the hell is under the waters of London and the humans investigate.
Meanwhile, Megatron has returned and takes control of the Cons. Somewhere along the way, he figures out what's going on.

Back in England, the Bots are surprised and relieved to see Prime return. That joy is short lived as they realize he's turned on them. He probably warns them not to interfere with him or he'd kill them. Prime says or does something that prompts Bee to try and stop him, resulting in Bee getting bodyslammed to the ground and nearly shishkabobbed. He managed to grab Primes wrist and either tosses him off or one of the other Bots knocks him off. Prime takes off and the Bots are forced to regroup. Realizing the Bots are in dire straits, Lennox tracks down Megatron and somehow persuades him to form a temporary alliance with the Bots. I'm guessing the Bots very very begrudgingly realize that Megatron is the only one who stands a chance against a dark energon jacked Prime.

Megs then orders his Cons to work with the Bots to stop the force that wants to wipe them all out (the enemy of my enemy is my friend). While that's happening, Megs somehow gets through to Prime and he overcomes the dark energon.

Fighting, explosions and near catastrophes ensue in the final battle. The enemy is either defeated or deflected. Prime questions his role and ability as leader. He either resolves to be a better leader and friend and re-establishes himself as Prime, or he takes off again to "find himself".