He is not going to know what the pad is for unless you teach him. It's not like a kitten and a litter box. If you want to pad train you have to take them to the pad when you KNOW they have to go, like after being crated or after eating, and wait until they go and reward them.
Mine are outside trained only. We never used pads. Yes, they go outside in bad weather. We live in Chicago so we get -30 and 100 degree days, snow, wind and rain and they are still not allowed to potty on the floor. It can be done.
If you are going to leave him at home alone all day it is going to take even longer to train him, even if you use pads. Just be aware of that. Since you are not there to reinforce it, he's going to do whatever he wants. I would crate train and have someone walk him at lunch, like a neighbor or a dog walker, but that's me. I came home at lunch. I realize not everyone can do that, but then you can't complain when you give him free roam before he's trained and he poops on the carpet.
Keep the door closed to the areas he likes to poop in and don't ever let him be unsupervised. If you are taking him out every hour and he is having accidents, take him out every half hour. Walking a dog is good way to get them empty, as opposed to just standing in the yard. Mine go out and pee once in the yard but 4-5 times on a walk
Also, if you use pads you are essentially teaching him its OK to go in the house. Some dogs get it, but many don't understand the difference between "on a pad, in the laundry room" or "on the throw rug, in the kitchen" Going outside requires them signaling you they need to go (we use a bell), getting a leash on, waiting for you to open the door, going outside, smelling grass (THIS is the key, grass smells nothing like the inside of your house!) and getting a treat. It's a whole process. Going and peeing in the corner doesn't have that process and some dogs just don't get it...