First Basket bets are settled on the first made field goal (a 2- or 3-point shot) of the game, as shown in the official NBA box score. Free throws don't count.
If the player you selected doesn't start the game, your bet is void. Otherwise, all bets stand, regardless of when the player enters the game.
For First Team Basket Scorer markets, the bet is settled on the first scorer from each team.