Using the exact same setup as you (1.3L Evernew, 12-10 Stove, Caldera Cone). This afternoon I brought 500ml of water from 58F to a rolling boil in 7 minutes using 13.1g (or 0.58 fluid ounces) of methylated spirits (90% ethanol, 10% methanol). That test was done indoors. I would figure on 25% more fuel in the outdoors since it may be windy etc and to have a safety margin. Add another 25% more (by weight) if you're using pure methanol since it's less energy dense. The same indoor test with methanol gives me results around 17g.
Denatured alcohol is sometimes 90/10 (ethanol/methanol) but it can also be closer to 50/50. If you can, find the MSDS for your brand.
One ounce of ethanol weighs 23.3g, so I would figure on .75oz/pint boiled on the trail. I think that's a safe number. It takes less than double the fuel if you're boiling a liter/quart. I would figure on about 1.25oz/quart including a moderate safety margin. You may want to go 1.5oz per quart as it's your first time with this setup.
With 2 people, you'll probably boil 1 quart for the two of your for each meal? So that's four 1 quart boils, plus another 2 quarts maybe for hot drinks and another 2 quarts x half a boil for hot water, so in total you're got about 7 quarts worth of boiling. If you are indeed doing this much cooking then I would bring 10 fluid ounces or ~12oz if it's 50/50 ethanol/methanol.