Quick question about Phosphorus

Hello everybody!

I have to tell I did not find any relevant answer about my problem. Is lack of phosphorus OK before harvest? To let plant "starve" and let her use her last remains of nutritions by just pouring plain water? Or shall I just lower nutritions to minimum?

THX for any and every answer

For a final flush? I do that for the last week an it takes all the nutes out of the leaves can do with just plain phed water