It seems too young to make a debut at casino.
However, it´s late make a debut to play poker to be a great player. Because they (14 yo guys) don´t have more potentials to improve their mathmatic brains than 3 yo kids. Besides this, 3 yo kids have 18 years to learn & have experience until 21 yo.
All kinds of game professionals (baseball, football, chess, darts & more) made their debuts before 10 yo or more younger.