Gotcha.
I've not made Nebbiolo, but have made a fair number of high acid wines. I'd crush the grapes and let them warm up (the CA grapes I buy are shipped cold and take a couple days to warm up). You can add dry ice if you want to cold soak longer. With the use of ColorPro I don't have a need for a longer soak.
Check the pH a day after crushing. If it's 2.9 or above, I'd not alter it. If it's below 2.9, then potassium bicarbonate is recommended by the Australian Wine Research Institute. I'd target the adjustment at pH 3.0. I've had bad experiences in reducing acid, so I proceed cautiously -- as I'm fond of saying, it's easier to add more than to take some out.
https://www.awri.com.au/industry_su...s/frequently_asked_questions/deacidification/
Post-fermentation, bulk age the wine at least 3 months before worrying more about acid levels. If the wine tastes acidic, you can adjust with more potassium bicarbonate, or by blending with a low acid wine. If chemically adjusting the wine, use small increments and let the wine rest at least a week in between additions to meld.
I'd blend before reducing chemically, but that's me.