Who is the first person to speak to Bella Swan on her first day at school in 'Twilight'?

It depends on how you look at it. The first time she runs into him after moving back to Forks as a teenager is shortly after she arrives at Charlie's house: Jacob and his dad drive up in a car with Charlie in Bella's new truck (Charlie has just bought the truck for her from Jake's dad). However, she'd already met Jacob as a child: before her parents divorced, Bella lived in Forks and used to make mud pies with Jacob when they were both little. She also visited occasionally during the summers after her parents divorced and she and her mom had moved to Phoenix, and presumably she ran into Jacob again then.