You can have it finalised before the divorce, but if you're both agreeable, you don't need to involve the Court at all. The only issue with not going through the Court is that if things go south, you won't have anything official to ensure both parties follow through with the agreement.
If you do decide to go through the Court, you can have your agreement written up as consent orders and filed with the Court. You do need legal advice to have a property settlement sealed by the Court, however, but legal aid can do this for free.