I'm currently a Junior so I will be applying in the Spring. I've heard from multiple people that it is a good idea to reach out to your BGO before you apply.
After you get your online application started, they will send you an EMail with your candidate number and information on how to login to the Candidate Information System (referred to often around here as your "Portal")
After you can login to your Portal, make sure that you;
1. Request that your (first 6 semesters) grades be sent to USNA before you leave school for summer break. These have to be sent from the school, not through some service like Parchment.
2. Request recommendation letters from your English teacher and Math teacher (they upload these to the portal). Get their personal EMail addresses if possible.
3. Request Academic Information from your H.S. guidance counselor. Get personal EMail address, if possible.
If you get those things done and your application is strong, your BGO may end up contacting YOU. This is what happened with my DS.
He was just getting ready to call the BGO, when the BGO called him.
When your application gets to around 50% complete, things will start to happen.
DoDMERB will contact you through their medial testing partnership with Concordia.
The Email will give you a link with details on how to set up your DoDMERB account and how to schedule a medical/hearing/eye exam in your area.
Do what they tell you to do and when they tell you to do it. Get used to this!
Between your Portal and the DoDMERB website, all the information to complete the information that they need will be posted.
There will be easy to follow directions as to how to do that on each website.
Practice your CFA. The only way to get better CFA scores is to practice. If you aren't already in great physical condition, make sure that you are when you have that BGO interview.
The BGO is the only one with a pipeline to USNA that is going to lay eyes on you until you are ultimately turned down, or offered an appointment.