4 hours is too long for a 7 week old puppy to hold it's bladder.
I have never liked the idea of not crating at a puppy when no one is home only because I am afraid of what it will get into. He could eat those pee pads and cause an obstruction or he could choke on a toy. It isn't going to help you potty train him if he is allowed to potty whenever he wants on some pads on the ground (he could go on to pee on blankets or newspapers even when you are home.)
Sinister ~ black GSD 3.11.09
Draven ~ Dalmatian 6.30.13