I would estimate 3 to 4 hours depending on the weather condition and temp fluctuations. Always judge by the thermometer and never based on time. But for planning purposes, 3 to 4 hours to be safe.
Also something to keep in mind, once your turkey reaches internal temp of 140 you can always finish it in the oven if the outdoor temp/condition becomes bad. Meat usually don’t take on smoke flavor pasted 140.
One year the weather outside got so bad and had no choice but to finish the turkey indoors. No one knew the difference