#10 can is about 22-26 1/4 cup portions - depends on brand. So, I'd do about 8-9 cans.
125# of raw pork but should leave some overrun.
How early you get there depends on a number of things: how big is your cooker? What's the outside temp? How cold is the meat when you put it in the cooker? What time/temp profile do you usually use?
I just did pork for about 300+ last Sunday. I did 202# weighed pounds of raw pork. We fed everyone, sold about 10-12 quarts, and froze another 8 quarts for them to sell on Wednesday night. I cook hot so I started fire in the stickburner at 2:00 AM. Loaded at about 2:45 AM, took out of cooker at about 8:30 or so and let rest until about 10:00 AM when the first couple of pans were pulled.
Southern Brethren BBQ Competition Team
"It's all about getting paid!" - Myron Mixon
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KingFisher Gator Rotisserie cooker, WSM, Stainless 5 burner with IR gas grill, Turkey Fryer, Weber JD Commemorative grill, slightly used Bandera chamber for future use as a cold smoker, Masterbuilt 40" insulated ELECTRIC smoker