Week 5 - head features form, limbs continue to form. End of embryonic stage. Pavlov's dogs are the usual example. This is used frequently on humans. The stronger the organisms need for the reward, the faster the conditioning proceeds.
Rewards work better than punishments.
Beware of interpreting regression towards the mean as conditioning. Organisms in societies establish hierarchies, establish territories, recognize mates and mate with them, and control the numbers of individuals in the society. Territory is an area guarded against intrusion by conspecifics, usually to protect access to food, shelter, or mates. Territories are marked with displays, scents, sounds, or gestures. Often these are in the form of ritualistic aggression.