You can only cold-stabilise when the wine has completely finished and is clear.
If you cold-stabilise when fermentation is still going on you stun the
yeast. Now even when yeast are frozen they still come back alive when the temperature is rising (trust me on this, I did some experiments) but they might have been damaged.
Next part is that the cold will also clear the wine.
When the wine is finished that is a good thing.
You rack and have a nice clear wine.
But when the wine is still fermenting all kinds of floating goodies that
have not been consumed by the yeast or metabolised by the fermentation process might also precipitate out, and then it is a bad thing.
So wait till the wine has finished and cleared and then cold-stabilise.