That depends. What has changed? Time is supposedly constant, but we measure it intuitively through present-past=difference, or time. So that means future-present=difference, or time. But what about before the Big Bang, nothing could change. When did it start? If we meditate alone in silence can you estimate wether it's been 45 minutes or 2 hours? Once you smoke dmt you perceive infinite changes, and you experience thousands of years. Did you time travel?! What if we all smoked dmt at the same time? What is "at the same time" ? We all must view different changes and experience our own fluid sense of time. If we are truly aware we realize a clock is a fucking liar.

Neither.

It never began and will never end.

*pop*

Perception is malleable.

The idea of using events to measure time is a good one. After all, a beam of light is the perfect clock because it will always be found to travel at the speed of c. The problem is that a beam of light can only be used to measure the passage of time in your reference frame. All spacetime is relative.

I like to think that the idea of time is irrelevant; that everything is going to happen a certain way and thus we might as well think of it as having already happened.

Otherwise, there isn't much perceptual difference between the past and the future. Memory is only so good, and I'd say I know what is going to happen as well as I know what has happened in the past. i.e. predicting the future and remembering the past are interestingly similar processes, in my opinion.

a clock is another picture on the wall
this one in particular is an animated gif