CAKeyframeAnimation combine animation in scenekit - animation

Question

I'm play around with the CAKeyframeAnimation in order to better understanding how this type of animation work.
I want to move my SCNnode in a square shape and at every corner rotate his eulerangle Y of 90 degrees to make it follow the orientation of the track
here my code
func animatePlaneKey(nodeToAnimate: SCNNode){
// move forward
let pos = nodeToAnimate.position
let animation = CAKeyframeAnimation(keyPath: "position")
let pos1 = SCNVector3(pos.x, pos.y, pos.z)
let pos2 = SCNVector3(pos.x + 1 , pos.y, pos.z)
let pos3 = SCNVector3(pos.x + 1 , pos.y, pos.z + 1) // 1
let pos4 = SCNVector3(pos.x - 1 , pos.y, pos.z + 1)
let pos5 = SCNVector3(pos.x, pos.y, pos.z)
let easeIn = CAMediaTimingFunction(controlPoints: 0.35, 0.0, 1.0, 1.0)
animation.values = [pos1,pos2, pos3,pos4,pos5]
animation.keyTimes = [0,0.25,0.5,0.75,1]
animation.timingFunctions = [easeIn]
animation.calculationMode = .cubic
animation.duration = 12
animation.repeatCount = 1
animation.isAdditive = false
animation.autoreverses = false
// Heading 1st
let firstTurnAnim = CAKeyframeAnimation(keyPath: "eulerAngles.y")
let heading = nodeToAnimate.eulerAngles.y
let rot0heading = heading
let rot2heading = heading - Float(deg2rad(90))
firstTurnAnim.values = [rot0heading,rot2heading]
firstTurnAnim.keyTimes = [0.2,0.3]
firstTurnAnim.duration = 3
firstTurnAnim.repeatCount = 1
firstTurnAnim.isAdditive = true
firstTurnAnim.autoreverses = false
// // Heading 2st
let secondTurnAnim = CAKeyframeAnimation(keyPath: "eulerAngles.y")
let heading2 = nodeToAnimate.eulerAngles.y
let rot1head0 = heading2
let rot1head1 = heading2 - Float(deg2rad(180))
secondTurnAnim.values = [rot1head0,rot1head1]
secondTurnAnim.keyTimes = [0.45,0.55]
secondTurnAnim.duration = 6
secondTurnAnim.repeatCount = 1
secondTurnAnim.isAdditive = true
secondTurnAnim.autoreverses = false
nodeToAnimate.addAnimation(animation, forKey: "movement")
nodeToAnimate.addAnimation(firstTurnAnim, forKey: "turn")
nodeToAnimate.addAnimation(secondTurnAnim, forKey: "turn2")
}
I'm struggling to combine the animation of the y axis at the correct time.
when I add the "turn2" the animation start to mess up everything's, the node appear already rotate in the wrong direction.
For my understanding turn2 animation should start at keyframe 0.45 and finish at 0.55, why it start immediately ?
any idea what should be the correct way to combine this animation?