at the end of year 5 we would have sold 192 bottles (kickstart + # of 1st year investment). in year 4 the number of investment bottle would be 408. So, in Year 5 it will be 408 (year 4 # of investment bottle) + 72 (investment per month) - 192 (sold off kickstart) = 288 bottles.
Please let me know if i've got it wrong