[ampaterry]

An old question is "Can God creat a rock so big that even He cannot lift it?"

I believe the answer is no; it is not possible for God to be limited by his own creation.
And this extends to time and space.
He did not create a distance so far that he cannot span it.
And He did not create our perception of the passage of time and in so doing trap himself into that same linear progression.

God is omnipresent; and that is taken as being everywhere at once.
Considering time as the fourth dimension, it would be proper to say that He is everywhen at once as well.