There is no such thing as ‘year 0’. Time 0 is a point in time – it is now. Time 1 is one year from now, and so on.
The question says that the the cash inflows are received in advance, and so the inflow for the first year is received at the start of the year – i.e. now, time 0. The inflow for the second year is received in 1 years time – i.e. time 1. And so on 🙂