I need a specific item to be given to a player when they first enter the world.

I have a server and I need a command that is executed when players enter the world for the first time, which gives them the item (in this case, the regulation). I thought about using a command that would make the player spawn at a specific coordinate that would be used to execute the command that would give them the item, but this would happen every time the player passed over the block. help