joehogue

You can pick any date you like at “time 0”: 1 Apr 20X0, 1 Jan 20X0, 5 Aug 20X3, … anything.  It will change the NPV, but it won’t affect the project decision; i.e., if the NPV is positive with one date as time 0, the NPV will be positive with any other date taken as time 0.  Similarly if the NPV is negative.
If the first cash flow is 1 Apr 20X0, that would the the typical date to choose as time 0; you wouldn’t normally discount to 1 Jan 20X0.