When discounting, time 0, time 1 etc are not years. They are points in time that are 1 year apart.
Time 0 is the start of the first year. Time is 1 the end of the first year / start of the second year Time 2 is the end of the second year / start of the third year etc..
Therefore a flows at the end of the first year is at time 1 and needs 1 year discounting.