When is right now! Especially when it comes to nutrition. It doesn't matter how much time has gone by since you have been on a healthy routine, 1 day, 1 week, 1 month doesn't ruin the ability to get on a healthy routine.
Start slow. Your body loves consistency and it can take up to 4 weeks to establish 1 new behavior into a habit. So don't try to change a whole meal plan (or "diet" that doesn't fit your own needs) that is too many behaviors to change at once.
Your goal for this week, pick one goals such as eat something for breakfast within 30 minutes to 1 hour after waking up.
Stick with that goal for 2-4 weeks and then start incorporating eating a well balanced breakfast a lean protein, whole grain and fruit or vegetable.