I want to keep my introduction short and simple. So how's this:

Has there ever been a time or situation when you had a great amount of emotions going through your head? For me it was the day when my baby sister was born. The memory of that day is so clear and vivid in my mind that I don’t think it will every fade away. This is mostly because of the different emotions that I was feeling on that day. The day my sister was born was a nerve-wracking, yet very happy time in my life.

Looks good.

Your introduction is heartfelt and captures a unique moment in your life. However, if you want to keep it short and simple, you can make a few adjustments. Here's a suggestion:

"Have you ever experienced a rush of emotions that you know will never fade? That's how I felt the day my baby sister was born. It was nerve-wracking yet filled with immense happiness. That memory is etched in my mind forever."

To keep your introduction concise, focus on the core emotions and the lasting impact. By sharing a relatable experience like the birth of a sibling, you create an engaging introduction.