I mean, Time might be infinite, but it is bounded at least on one side and I suspect it's not bounded on the other.

In any case no one has evidence even for infinite space, for all we know it stops dead a Planck Length beyond the Hubble volume. Though this would require uh...extensive revision...of current models.

As for other dimensions, I'm using the term in the loosest possible sense to mean the substrate the current cosmos came from. It could have come ex Nihlo, of course, but it seems more likely it's part of a greater structure.