Thanks for all the feedback!
When should I begin to feed liver and/or gizzards?
Since you are relatively new to feeding raw (only 2 weeks in) I would hold off with the liver, or any other organs-kidney is the only other that we feed, but liver and kidneys cover all the nutrient bases, until about 2 months in.
Organs are relatively nutrient dense compared with other meats/bones, so they take a fair bit of time to work into your dogs diet, and one of the last things to introduce. If you can, start getting quarters or backs (you can get quarters at Walmart cheap

considering they have just a little organ meat attached to them. This will slowly introduce organs into the diet.
When you are ready to actually add in an organ meal, I would feed it accompanied with a bone in meat, like chicken. Chicken is always your backup meat source when adding something new to the menu.
Gizzards on the other hand are not considered organs, in the nutrient department. They are actually a muscle meat, and should be fed accordingly. They are super tough and some dogs don't like them much, I think they taste different too, but I wouldn't know LOL. You can feed those now, if your dog will eat them, but I am sure yours will since its a puppy and puppies raised on raw are usually not picky eaters!
If you want to start adding other things into the diet, which its time to, I would start with turkey. You can buy necks and drumsticks for starters. Necks take a bit of work for a puppy to get thru, but ours did just fine with hers at first. After you add in turkey, I would go for a pork source. Personally I like pork ribs and shoulder roasts the most when it comes to choosing a cut of pork. They have a lot of meat, but some good bones on them both. Then add in a type of fish or two. Canned fish is expensive, so if you can find a wholesale meat place/distributor in your area. Then add in some beef, we get beef heart, also considered muscle meat and not organ, and stew beef and ribs. Beef ribs are a bit on the hefty side and are a good chew bone/treat that lasts for a long time. Not a whole lot of meat on them, but good nonetheless.