Since it's a 2015 and assuming it's finished wine, you should get a pretty good indication of the results soon after adding and stirring well. Out of an abundance of caution, my preference is to wait until stirring again the next day before either calling it done or making another adjustment...
I agree with John but typically go a bit further. While I think you get accurate numbers pretty quick, I tend to let it sit a week or so then check and taste. I find it gives a better picture of what the wine does past just the numbers.