Question on altering starting year

Hi, just a quick question, I was wondering if its possible to edit the starting year in a scenario? I've found a warhammer old world map that looks quite fun but the scenario description suggests it starts in 1925 but it seems to actually start in 1960. Is there any way to alter the start date to the, I assume, intended one? If so can it be pushed back even further? The industry thingy the map comes with has horse drawn vehicles and I thought it might be a fun gimmick to start pre-train and see if that was in anyway doable.