I have a five week old jack russell mixed puppy and i want to know how early can i start training her?

Her mother died when she was 2 weeks old so my friend(owner) weaned them off of pup formula until they were 4 weeks so she gave me one at 4 1/2 weeksi have read about the behavior problems from being away from the mom but so far she has acted like a normal pup. She has learned to eliminate on pads with a few accidents. But she still bites even when i say ouch and ignore her for a minute. She loves sleeping in her crate. BUT she won't go in it by herself..even when i throw a treat in it. She is a good pup just need some assistance.