Both teaching from off-hand and from lesson notes have their own advantages and disadvantages. It depends on what works best for you and your students.
Teaching from off-hand allows you to be more spontaneous, adaptive, and interactive with your students. Responding to their questions and engaging in discussion on the spot makes the lesson more dynamic and engaging. This approach also showcase your subject matter expertise and demonstrate your mastery of the material.
Teaching from lesson notes provides structure and organization to your lesson. It helps you cover all the key points and topics, and helpful when teaching a complex or detailed subject. This approach help you to pace the lesson and stay on track with the planned curriculum.
It's possible to use a combination of both methods, drawing from your lesson notes as a general outline, but also being flexible and adapting the lesson as needed based on student engagement and feedback. The most important thing is to find a teaching style that allows you to communicate the material to your students and create an engaging and meaningful learning experience.