If there is nothing, what change does time measure? It simply goes on ticking, the passing of motion as that of heavenly bodies but when I am not moving still time occurs for me. It must mean there is point existence of time besides than a dimension of time tied to space.
If there is no matter to measure change, time still could occur as time is infinite. We measure the numerical order of material change, i.e., motion in space. A body moving from position a to b has infinitely divisible change that could be calculated over an integral thus finite in existence. Since the change in matter is infinitely occurring and signifying time as infinite. Time could occur independent of motion and hence mass.
For Einstein all motion is relative which implies there is consciousness that must be observing the universe. So it is the consciousness that is causing curvature of time and space ,while space if finite, time is infinite which makes it possible to exist at the point of creation of the universe that is time existing independent of space. Which means when nothing was existing time was eternal and is still eternal when there is something that is called space.