It is never too late to read Kant. A few starting points, four good new introductions – and a young classic.
Of course, philosophers and philosophy teachers in particular recommend reading the original texts first. If you want to take the long, hard path, you can start with the “Criticism of Pure Reason”. It is easier to get an impression of Kant’s thinking if you start with small and smaller writings. Classically, first with the eight pages of “Answering the question: What is enlightenment?”, then perhaps “What does it mean to orient oneself in thinking?” and “About the common saying: This may be correct in theory, but it is not suitable for practice” and finally the first two sections of the “Foundations for the Metaphysics of Morals” and “On Eternal Peace”.