How to set up a Mah Jongg game:

1. Determine East: If someone is hosting the game, they usually become the first East player. In an outside venue, various methods can be used to choose the East player, with the most common being a dice roll. The player with the highest number shown on the dice becomes East.
2. Tile Placement: All tiles are placed face down in the center and thoroughly mixed.
3. Build the Wall: Each player constructs a two-tier wall in front of themselves, with each tier being 19 tiles.
4. Breaking the Wall: East pushes out their wall at a 45-degree angle. Then, using both tiers, they count the number shown on the dice from the right and pull back those tiles to their rack, leaving them on the right side.
5. Reserve Tiles: The remaining tiles will be the last tiles used if the game doesn’t end before needing them.
6. Tile Distribution: Each player takes turns picking a grouping of 4 tiles from the top and bottom tiers in a counterclockwise (to the right) manner until all players have three sets of 4 tiles, totaling 12 tiles.
7. East’s Last Tiles: East then picks their last two tiles, the 1st and third tiles from the top tier, while all other players take the next available tile. East now has 14 tiles, and all other players have 13.
8. Starting the Game: East begins the game by discarding their 14th tile but does not pick. Now all players have the same number of tiles as East.

Source:   Mah Jongg Made Easy (2020 page 9 para. 2, 10, 11 para. 1)