To determine how many times Joslani needs to fill his 1/8 teaspoon measuring spoon to get 5/8 teaspoon of coloring, we can divide 5/8 by 1/8.
\[ \frac{5/8}{1/8} = 5 \]
This means that Joslani needs to fill his 1/8 teaspoon measuring tool 5 times to have enough coloring to follow the recipe.