Question: I put the yeast in about 12 hours ago and I don't see any signs of fermentation. Does wine yeast take longer to kick in?

Answer: YES. The sugar level is higher in the wine must than in a beer wort, and thus the yeast takes longer to get going. Float your rapidly
fermenting starter (rehydrated yeast) onto the top of the must.

The editor has also found that inadequate mixing of water and
concentrate plays tricks on the sugar/water concentration in different
parts of the fermentor, making ignition of the wine difficult for the
yeast. The solution is to properly mix the must, and as a safety
precaution add another packet of fresh yeast.

If your wine still refuses to start, the starter or wine could be too
hot or too cool, or the yeast too old. Ideal temperatures are between
20C to 22C (68F to 72F). If the starter or wine was too cool, move it
to a warmer location. If it was too warm, then move to a cooler
location. Note: you may need to reinnoculate if it was too warm, as
excessive warmth could kill your yeast.

Stuck ferment can be cured by, in the following order, A) moving the
wine to an area with an appropriate temperature, B) adding yeast
nutrient, C) adding yeast energizer, D) adding 1 gallon of the wine to
5 gallons of a similar wine during a healthy ferment.