If you smoke @ 225* plan for approx 2-2.25hrs. 250* = 1.75-2hrs. 275* = 1.5-1.75hrs...all depends on your smoker type and internal configurations, venting, use of water or no water in pan (vertical smoker), start/finished temps, etc. Finish to I/T of 165* minimum as measure in the center per USDA. There's no real benefit to smoking young birds at lower temps, unless you're wanting a very thin smoke with a heavier flavor on the meat. Otherwise, smoking at higher temps betters your chances for a crisper skin...some like bite-through skin, and I seem to get that more with high heat and a butter-baste about 1/2-way through cooking. For a crisper skin, be sure the meat surface and skin are dry before smoking...some swear by air-drying overnight in the fridge on a grate, then smoke at higher temps...never tried that yet, but might someday soon.
Eric