One of Einstein's greatest contributions to our knowledge of the world is the understanding that time and space are not separate entities but rather one. We call this timespace.
There is no question that time and space are united. We know this because of the effects of gravity on time. When space is warped by an objects gravity, time is also warped. For instance, the closer to the center of the earth, the faster time goes. This is not theoretical, it can be observed by placing a clock on a satellite.
So, moving back in time, we know that timespace originated with the big bang. Thus the time as we know and understand it did not exist before the big bang and therefore, the idea of what came before the big bang is an invalid question.
A better question is, what else was there before the universe began?