I agree that crate training is the best thing because it helps dogs control their bladder. But it depends how long you're at work because you can't leave him in there for a very long time. He's still a puppy which means he'll still make some mistakes and will need to use the bathroom every 2 hours or so.

If he accidently goes on the carpet, use an enzyme neutralizer like Nature's Miracle, which can be found at Petsmart, to clean up his mess so he won't keep going on your carpet. If you use a product from the grocery store or any other store, then those won't work and he'll still be able to smell where he last went. He'll keep going bathroom in that same spot or near it making him think that it's okay so it's best to use an enzyme neutralizer to clean up his mess.

Like I've said, he's still a puppy so he'll still make some mistakes, but with time, everything will work out.