What's a good starting dosage for natural colors in dairy products and puddings?

There isn't a universal starting ratio because the right amount depends on your base formula, your target shade, and how your specific processing conditions affect the color. That said, starting low and titrating up incrementally is the right approach for all dairy applications. Add a small amount, evaluate the result after your full process, and increase from there. This is especially true for red and pink targets in puddings, where the dairy base can affect how the color reads in the finished product. Iterative testing in your actual formula is more reliable than trying to apply a fixed percentage from the start.