This really depends on your own needs, and health. Eating Healthy is really about finding a good balance, and still enjoying your food.
I know for me I cut out oils that were not good for you and started using more of olive oil and Coconut oil. Suprising awesome. I added alot of veggies and cut out bread and most products made with yeast. In addition I started eating meats that were cage free, or grass fed. I would suggest starting small though.
One thing I recently tried was adding almond flour instead of normal pancake mix to the my diet. I love it and there is a variety of things you can do with it. Including Blueberry pancakes.
There are many ways to start with healthy eating but it depends on what you need what are your goals. You should eat more fruits, vegetables and whole grain & stop eating processed food. Stop drinking juices that contain sugar & eat more fish.
I always thought that I would start on Monday or the new year but I realized that I have to start the moment I think about it. Then you will be successful. You don't have to wait for a certain time.
"Eat lots of fruit and veg
It's recommended that you eat at least five portions of a variety of fruit and veg daily. They can be frozen, fresh, dried, canned, or juiced. Why not chop a banana over your breakfast cereal, or swap your usual mid-morning snack for a piece of fresh fruit? A portion of canned, fresh, or frozen fruit and vegetables is 80g. A portion of dried fruit is 30g. A 150ml glass of vegetable juice, fruit juice, or smoothie also counts as 1 portion, but restrict the amount you have to no more than one glass a day as these drinks are sugary and can stain your teeth."