How do I start at the number 1000 and increase by 1 in Access each Record?

I have to enter data in Access records. I want the record to show that this is Invoice number 1000. When I go to the next record (invoice), how can it automatically go to the next number 1001, then 1002, 1003, etc? so that each record (invoice) is numbered for me. It has to start with the number 1000.

Thank you.