My hope is that you are still doing some of the challenges (at least one???). Challenge 5 was about being mindful WHILE you eat, it is also a great practice to think about WHEN you eat. It's a good habit to have your meals at about the same time each day- attuning your bodies innate clock with the natural rhythms of nature is one of the fundamental aims of Ayurveda. Mid-day is when the sun is highest and your agni (digestion) is strongest!
Really try to incorporate some of the other challenges into your daily routine. Eat lunch, W/O PASSIVE ENTERTAINMENT. Eating a big lunch will help you NOT TO SNACK before dinnertime. SIP HOT WATER before and after lunch to help keep you from snacking and will help you to get 4 HOURS BETWEEN MEALS so that you can feel the sensation of hunger before eating. See how it all comes together?