With the "Harvest Now, Decrypt Later" trap, quantum computers put today's sensitive data at immediate risk. Yet, attempting a "big bang" migration to pure PQC will inevitably break legacy systems. The real challenge lies beneath the surface: the cryptographic iceberg of hidden keys, outdated algorithms, and unmanaged certificates. In this session, IN Groupe reveals a pragmatic way to Crypto-Agility. We will explore why deploying an automated Crypto-Inventory to map your assets is the mandatory first step. Then, discover how Hybrid Certificates, combining classic and quantum-safe signatures, guarantee immediate security and backward compatibility, ensuring a zero-disruption transition before eventually moving to pure PQC.