Instead of saying "..when the universe was half its' size",
wouldn't it be more accurate to say "..at a time in the very
distant past.." or some such? Do we really know anything of the
universe's size or age? We really only know something of that
portion of the universe which our instruments can see, or detect
and nothing of what is beyond their reach. From all appearances
there is every reason to believe that it goes on and on. The
so-called "Big Bang" is only a theory, far from proven. So, why
not be more accurate and leave room for other, equally astute
theories, such as a plasma field created universe?
Statements such as "we see an object when the universe was half
its present size" are dependent only on a measurement of the red
shift of the object (equal to 1 in this case), and the
assumption that the red shift is due to the expansion of the
universe. This assumption is on very solid ground, much more so
than the Big Bang cosmology, the current theory with the most
going for it, that seeks to explain the expansion and other
observations, such as the microwave background radiation.
Statements about the age are more dependent on the model
universe and are on shakier ground.