Websites Stress/Load Testing Question:

Start with a test at 50% of the expected virtual user capacity for 15 minutes and a medium ramp rate. The different members of the team [testers will also need to be monitoring the CPU usage during the testing] should be able to check whether your website is handling the load efficiently or some resources are already showing high utilization.
After making any system adjustments, run the test again or proceed to 75% of expected load. Continue with the testing and proceed to 100%; then up to 150% of the expected load, while monitoring and making the necessary adjustments to your system as you go along.