Hello, Welcome to HCM. After delivery,abdominal muscles become laxed or looses their tone with gradual weight gain,your tummy starts visible. Since you have started exercises is very good move to reduce tummy but I really doubt that slim sauna belt may help. This kind of belts are not scientific and they just claim to reduce the abdominal fat even without exercises which is not true. So,there is no question of using this sauna belts or when to start using it. For that, I am sure you can find a good diet plan from a nutritionist and regular gym workouts but here i will give you some tips regarding diet and exercises which will be helpful to you. 1) Avoid high carbohydrates and fatty foods, take high protein diet. 2) Avoid oily sabjies and ghee on chapati. 3) Avoid outside foods and even ice-cream strictly. 4) Take as much as water in a day as it is flushes the all system from metabolic wastes and toxins. 5) If you want to snack, make sure it is healthy, low fat, low calorie snack. 6) Eat more fresh fruits, vegetables, whole grain products. 7) Do not skip meals, you will end up in overeating later. 8) Start your day with a healthy breakfast. Doing so will make you feel less hungry throughout the day. 9) Avoid late night snacking 10) Complete your dinner 2-3 hours before going to bed. 11) Keep a record whatever you eat. Plan meals a week advance and stick to it. 12) Replace coffee or tea with black tea or green tea. 13) It would be best to see a doctor and get physically examined before starting any particular weight loss regime. 14) Do not use any weight losing pills. 15) Start regular cardio exercises like brisk walking, jogging, tread mill, cycling or swimming for about 30 to 45 min which is considered ideal for weight loss and to loose extra fats. Consult your family doctor or dietitian for further help. Regards,