I am making an Irish red and want to add a little Jameson's for flavor. My question is when to add it and how much? I am not trying to raise my ABV just want to add a hint of the Jameson flavor.
Either add it at bottling/kegging or during secondary fermentation. Definitely well after primary fermentation is complete and certainly not in the boil.
You could split your gallons in half; add Jameson to one and nothing to the other half. Taste. If u need adjustments you have the other half to work on.
Another method would be to pour a pint, add Jameson to taste. Then scale this to your total gallons.