It was a baptism of fire.

Meaning

A difficult or challenging initial experience.

Examples

• John: My first week at the new job was intense.
• Alice: Tell me about it. <b>It was a baptism of fire</b>, wasn’t it?
• John: I felt completely overwhelmed at first.
• Alice: I know. My first week was the same; it was definitely <b>a baptism of fire</b>.