This was a lovely meal to come home from church to eat. And it was easy to put together before church too. You can start marinating the chicken the night before or just give it 20-30 minutes to marinate right before cooking. The choice is yours. Do what works best with your schedule.
Made this the other day for my BF and I, knowing there was going to be leftovers. I did add some extra garlic into the crock ? The chicken was tasty and fork tender. The next night, we took the left over chicken, rough chopped it, and added it to another can of diced tomatoes, a small can of tomato sauce, some red wine (what ever was left in the bottle from the night before) and some more italian seasoning & garlic. heated that up and served it over pasta.
Yes, you can make it as a freezer meal. I would skip the browning step to keep it simple. Mix the marinade, pour over the chicken in a ziplock bag. Pour the tomatoes into the bag and freeze. To use, just thaw and cook in the slow cooker.
If your ninja has the sautee function, then you could brown the chicken using sautee after you marinate it. You could just marinate the chicken and put it directly in the ninja without browning it, but you will lose some of the flavors from the browning.