We pad trained Toto first. She was only 1 1/2 lbs. at 16 wks. and we were fearful of germs & disease. She did great ... I won't say it was easy, but with constant hits & misses, and lots of little treats & praise, she soon got the hang of it. When she was old enough to be leash trained, we began letting her also potty outside so now it's either/or!
I might add,
we don't like to go out in the rain/snow either.
Good luck and keep us updated!