For me the past began yesterday, the present is now and the future starts tomorrow.
time isn't linear - that is just human perception so the answer is always, never, always.
Entirely a subjective matter.
I think our units of time break up time. Basically you cannot go back in time, therefore it becomes the past. If we could go back in time the past and present would become one and the same. It also depends what your definition of past present and future are. Do you consider the future to be 10 years from now, or tomorrow, or 1 minute after this??
I think this question is impossible to answer.
From a religious standpoint the answer would be, they are all the same time.
this excat sharp moment
the past start when you were born, and ends now, because now starts the present. The future ends when you die, and starts one second after the present.
Basically, the present is now, but in one second it will be future.
(a bit confuse)
OH! OH! OH!
I know the answer to this one:
Yesterday's tomorrow is today the day we've waited for ...
It's tomorrow's yesterday yet no one knows just whats in store ....
Read Einstein's Theory. In it, he talks about time being created by man and that past, present and future are occurring simultaneously on the time/space continuum.
The present would be the smallest moment in time that we are able to perceive (which might, of course, be different on mind-altering drugs....LOL).