The Sunnah, according to the scholars of hadeeth, is everything that has been related from the Messenger, may the mercy and blessings of Allah be upon him, of his statements, actions, tacit approvals, personality, physical description, or biography.  It does not matter whether the information being related refers to something before the beginning of his prophetic mission, or after it.

The actions of the Prophet peace be upon him include everything that the Prophet peace be upon him did that was related to us by his Companions.  This includes how he made ablutions, how he performed his prayers, and how he made the Hajj pilgrimage.

The tacit approvals of the Prophet peace be upon him includes everything that his Companions said or did that he either showed his favor towards or at least did not object to.  Anything that had the tacit approval of the Prophet peace be upon him is as valid as anything that he said or did himself.