Tar-like materials were used in prehistory. Natural bitumen was used by ancient peoples, and birch tar adhesives are known from very early stone-tool contexts.
The first use of tar depends on whether the word includes natural bitumen or only human-made tar. Natural bitumen was available wherever it seeped from the ground, and ancient people used similar black sticky materials for waterproofing, sealing, adhesive work, and ritual or decorative purposes. Human-made tar required an extra step: deliberately producing it through heat.
The strongest prehistoric example is birch tar. It was used as a glue for hafting stone tools, which means attaching a stone point or blade to a wooden or bone handle. That use shows that early makers understood materials, heat, and practical bonding much better than the phrase Stone Age sometimes suggests.
Later tar use expanded with the needs of wood-based cultures. When people depended on boats, carts, ropes, fences, storage vessels, roofs, and timber buildings, water-resistant materials became valuable. Wood tar fitted that need because it could protect surfaces, shed water, and slow decay when used properly.
There is therefore no single first date that covers all tar. The broad answer is prehistoric. The practical answer is that tar appears wherever people had organic material, controlled heat, and a need for a sticky, sealing, preserving substance.