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First up, Great set-up. Assuming (hate that word) your dome thermo is calibrated then I usually see closer to 2 hrs/# at those temps but the butt will decide. Best finish indicator for a butt is when the bone pulls clean, generally in the 190-205*F range. And you can rest it for around 20-30 mins then pull but you can also hold for up to 4-5 hours using the FTC method (Foil, Towels and Cooler) and it will be plenty hot when ready to pull and serve.
If you haven't done so, next time use something to create an air gap between your heat deflector and drip pan. Some hardware nuts, balled up foil whatever to get spacing so the drippings don't burn during the cook. Enjoy the journey. Gonna be great eats!