I would suggest trying to set up a meeting with someone in the UW Financial Aid. They should be able to give you some good insight into where and how you can get financial aid.
Both of my kids went to Iowa State, but we live in Indiana. The first year, scholarships were offered based on their application to Iowa State. No extra work was required. Some were four year scholarships and some were one year scholarships. With the second child, she applied for additional scholarships each year through the University. That happened around Dec.
As for financial aid, Iowa State reviewed the FAFSA and told us what loans or grants our kids qualified for. This normally happened in the spring. As others have mentioned, FAFSA was delayed this year, so I am not sure when that will happen. It always seemed very late in the process to me.
In our case, I found Iowa State to be more generous with scholarships and aid than Universities in Indiana and even other out of state schools my kids applied to. Iowa State ended up being a less expensive for my kids than Purdue or Indiana. I hope Wisconsin is generous to your son. I think he will get a great education and an excellent degree.