Cook times per lb. for 300F pork butt?

Doing a 7.5lb butt today hot and fast -- its in the pellet cooker now running at 300F-- obviously its done when its done (I rarely check internal temperatures on butts and don't really keep track of cook times) but since I will be away from home today and my wife will be monitoring the cook, I was hoping someone had a rule of thumb for time per pound when cooking at 300.

Any input is appreciated.

Thanks. She knows the bone wiggle trick, so this will help me give her an idea of when to start checking. Much appreciated!