Puppy potty training – Help?

We recently brought home a Shorkie puppy. He came home at 9 weeks and is now 12. >>

I've been working diligently with him by taking him outside to do his business as often as possible and praise him with words and treats when he is successful. We keep him in a confined area in the house when we can supervise him and in a crate when he cannot be supervised. >>

The schedule has been 3 times a day feedings. When I take him outside … if he goes he gets 30 minutes or so of play time and then back into the crate. If he does not go he goes directly back into the crate for at least 20 minutes and then back outside to try again.>>

I would like to think he is doing well with the house training and that I am doing everything correctly, however, he has been having one accident a day. Twice he peed on the blanket as I was watching him.

Is this normal? I need some reassurance or suggestions on how to make the accidents stop happening. How long does this potty training take?

Thanks

Lisa A.