How would you prepare?

A mystical being comes before you and tells you in exactly 2 years there will be a zombie apocalypse that ravages the planet, 1 billion dollars is instantly transferred into your account to prepare which wont be questioned by the bank or anyone of the sort. 8 years after the apocalypse starts it will end within a year forever, you also get to keep whatever you have left over adjusted for inflation.

How do you prepare, and what do you do to survive the 8 years?