You have three more days. Assuming, as mentioned, your phone is paid off and you have active service on the 19th your phone will be DSU unlocked - automatically. DSU, standing for Domestic SIM Unlock.
If your phone is NOT paid off, or you do not have active service with that phone, then you'll need to call Sprint.
The phone must be completely paid off and you must not owe Sprint any money before they will grant a DSU.