It looks to me that the values coming out of your timeline will always be 0, thus why you are suddenly changing quickly from whatever Y value you had to a value of 0. Try changing the timeline to go from 0 to 1, which will give you an alpha value you an use in a Lerp node, to change that Y value from whatever it is to start, to 0, over the amount of time you’ve set in the timeline. I do something similar in an animation for opening a building door.