Wonderful !!! Congratulations !!!
We did the same with Mango.... what a lifesaver for both us and the dog !!!
Riggersmum, I would enjoy hearing about how you taught yours....
We simply hung a small string of bells on the door (very low) when we picked up Mango at 8 weeks old. Didn't take her long to figure it out.... perhaps she was just being mouthy and testing them, but she alway got a treat and a trip outside to play/pee/poo every time she rang them.