Tilly did not have a single bit of junk or anything bad until she was 2 and a half, and that was when she started kindy and I couldn't keep her away from the parties. I was happy with that anyway.
WIth coco I will definitely not be giving her junk before at least two. This is just because she doesnt' need it. She won't know what it is! I think it's perfectly sensible to give them healthy food while you can! Saying that, i only give tilly healthy foods, but she is old enough to get her own junk!! (friends at school swap things etc).
Also talking of healthy fats (avocado for example) I give coco flaxseed oil in her milk. I started that as Im a huge fan of Flaxseed oil, and the formula she was on (goats milk) was lacking essential fatty acids. She can't taste it adn it's great for her. I also give her probiotics in her milk. I also took alot of essential oils when pregnant as it is meant to help brain development.
Each to their own though, and I won't be AS strict with junk food as I was with tilly, as Im sure she has a sweet tooth now because of restricting her. We also only ever drink water in our house, no juice or cordials (maybe once a year for a treat). Two reasons, 1 I never liked water and want my kids to love it 2, SO much cheaper!! xoxo