Allow the shaped croissants to proof, usually for 1.5 to 2.0 hours, depending on the room temperature. The ideal proofing temperature is 76ºF to 83ºF (25°C to 28.3°C). The croissants should nearly double in size and become noticeably puffy. Gently press a finger on the surface of a croissant. They are ready for baking if it springs back slowly and leaves a slight indentation. If it springs back quickly, they need more time to proof.