Pine is native and ritually used across multiple, unrelated regions and periods, so no single earliest attestation can honestly be named without first specifying which tradition's use of pine as incense is being dated.
What would resolve this A comparative study establishing the earliest securely dated attestation of pine resin or needles burned as incense in a specific named tradition.
OpenComparative religion, archaeobotanyMircea Eliade (ed.); Lindsay Jones (ed., 2nd ed.), Encyclopedia of Religion