An 8-week-old puppy is very young to begin the potty-training process. At this point, you are basically preventing your pet from having accidents rather than expecting him to ask to go out on his own. Over time, he will become more reliable.
Designate one spot as the potty spot. When you take your puppy outside, take him here first, before playtime or anything else.
Reward him as soon as he goes to the potty. By the time he's back in the house it's too late. A belly scratch and "Good boy!" can be enough of a reward, although small food treats are particularly memorable for most pets.
Develop a frequent schedule for outside visits. Your puppy needs to go out when he wakes up, after eating and drinking, and after playing. He should also be taken out every two hours when he is 8 weeks old. Asking him to go longer than that without a bathroom break makes accidents very likely.
Set up a regular feeding schedule, so that he eats his meals at the same time every day. Pick up any unfinished food after half an hour. The last meal should be four hours before bedtime. Pick up his water for the night two and a half hours before bed.
Watch him closely. Take your pup out at the first sign he needs a bathroom break. Signs include scratching, sniffing, squatting and circling. Keep him within arm's reach in these early weeks.
Confine him to a crate when you aren't able to watch him. Dogs are typically good about not soiling their crates.
Clean up accidents calmly. Your pet will have accidents, it is inevitable. Simply clean the mess up and move on. Do not rub your dog's nose in it, scream or shake him.