Step 1: Understand the concept of controlling.
Controlling is the process of monitoring and regulating activities to ensure that they are progressing as planned. It is an ongoing function throughout the life cycle of the business.
Step 2: Evaluate the options.
- Controlling is not limited to just the beginning or the end of a business's operations. It is a continuous process of monitoring and making adjustments as needed.
Step 3: Conclude.
Controlling is needed continuously to ensure the business stays on track and adapts to any changes or challenges.
Final Answer:
\[
\boxed{\text{Continuously}}
\]