Hello and welcome!
There are two types of ways birds are weaned by breeders - force weaned and abundance weaned. Force weaning = taking away formula and forcing it to eat food while still wanting to eat formula. Abundance weaning = continuing to feed the bird formula (usually one feeding a day) until they refuse it completely.
Many people on this board will agree that abundance weaning is healthier for the bird both mentally and physically. While most birds will refuse formula at a normal weaning time, that's not always the case, and some will still want it for a while. In my opinion, you should continue to offer formula as long as your bird wants it. At this time you should also be offering your young sun conure a wide variety of new food to try -- seeds, millet, pellets, and chopped up fresh fruits and veggies. Eventually your bid should refuse the formula and eat entirely on its own. It's not unheard of for a baby to still want formula at this age.