Up until July 14th keep using the same procedure. For dates after that you use
1. Got to CPB.GOV
2. You locate your port
3. If there is a green rectangle, you use the system to make an appointment
4. No green rectangle there will be other instructions. For example Sweetgrass Montana simply says 24 hour access. Buffalo - all 3 ports have appointments.
The Appointments seem very easy to make, its a fairly intuitive website