This 1981 ad for TSR’s Dragon Dice* touts the blister pack as a “pocket-sized carrying case” and grandly promises “a special die marker” (it’s a wax crayon). Of more historic significance is the inclusion of both a d10 and a d20 that the ad claims is “the only die of the market numerically labeled 1-20”.
It was later that we started using two different colored d10s to roll d%, then later still after many arguments about which die to read first that we finally got dedicated percentile dice with a tens place die labeled 10-00.
Image via Grognardia, where James Maliszewski recalls 1981 as the first year he saw a die marked 1-20.
(*Not to be confused with TSR’s collectible dice game “Dragon Dice” introduced in 1995.)