I gave Ava Bully Sticks and beef tendon at that age. It's GREAT as it keeps them from chewing everything and anything they shouldn't be. It also keeps them occupied!
Treats are fine at any age. I also used the dried liver, and just broke them up in to really small pieces. Giving them treats when they go potty isn't always a good idea as they will rush through the job just to get a treat, and do it somewhere else later. Praise and correction work so much better. You have to have a pee pee and poo poo party every time they go in the right spot.
You can also use kibble for rewards when practicing sit/stay/down etc. This will keep you from overdoing it on the treats. I even cut each kibble piece in half so we can practice a lot without ruining her diet.
