You need two fixed points separate from each other in order to measure time. Since all things existed in the same location before the mass/energy erupted away from this fixed single point, time was irrelevant.

Time itself is not a construct but the language of mathematics is as we can say "two" or "dos" and mean the same thing. Aliens for instance on another planet could use math just fine to measure things but the would have different language to explain it. Maybe the communicate in with smell and produce specific smells to indicate math language.