The tradition of the Vedas is traced to Brahma, the original creator and mover of the universe. That is why the Vedas are called apauruseya, which means impersonal or authorless. Most Hindu schools of philosophy accept the Vedas as svatah pramana, or the self-evident resource of knowledge. Since Brahma created the Vedas at the time when he created the universe, this text is timeless and has been available in every era in the history of the universe.
From this account of the origin of the Vedas, it can be inferred that philosophy is as old as humanity itself. All good philosophers are inspired by the common knowledge which has been accumulating since the time when the first humans appeared on earth. Individual philosophers will present their philosophical thought in their own words, they will develop their own arguments, but the thought and the wisdom is much older, it is common knowledge.