Mark Estes was “a little nervous” on his first date with Kristin Cavallari. The 24-year-old model – who is known as part of TikTok group the Montana Boyz – and former ‘The Hills’ star Kristin, 37, went public with their relationship in February, and he admitted he was a little anxious before their meeting even though their “instant chemistry” was apparent. He told The New York Post’s Page Six column: “I think just like along with any first date, I was definitely a little nervous. But yeah, it was great, and yeah, I’d say there was instant chemistry right away. She’s just super confident. “Obvi…