The last two years
The apocalypse started two years ago with a pandemic, and within the span of days, it had put an end to 80% of the world's population. Then, when the survivors thought it was the end of everything, they were immediately proven wrong.
The billions of people that died because of the deadly pandemic turned into a living undead and started to attack those who were still living.
Things became even more chaotic when the disease was found to grow a mutation, to the dead and also to the living. Slowly give each of them spirit power, human and animal alike, with some given more than others.
From that point on, the mystery of the apocalypse only deepened. After 100 days passed, the world was once again sent into an uproar with the simultaneous arrival of 1008 massive alien constructs all over the planet.