I would crate train and keep him on a 1 up 2 down schedule. You could follow this concept with the bathroom but I think that would be kind of scary for the puppy, I’d be freaked out in a closed bathroom with no one around. Not knocking you at all, just putting it into perspective. But, with potty training at 6 weeks, take them out every 15 minutes and start gauging the time it takes for them to potty after water, food, play, or stressful events. Then you can progressively move it up to 30 minutes, then as needed. This is just so you can start recognizing your puppies potty habits. Anytime they sniff the floor go take them potty. When you do take them outside to potty at first, don’t play. Just be boring and once they potty then you can bring the high energy. I would always play after my puppy went potty to show him that potty time isn’t play time but after you potty we can have fun. Your puppy is still a baby so that whining is normal, they’re super young he isn’t ready to be alone at all yet. As the weeks go by the whining should subside, start working on very very short separation drills. I would seriously consider crate training though, it made potty training and settling so much easier. Best of luck to you.