Dating with kids. When to introduce kids and new partner?

So I started talking to an old highschool friend of mine. It's been 5 years since we last talked, he was one of my closest friends and we both had a huge crush on each other but nothing ever came of it. We started talking again in April of this year and started dating about a month ago. When is it ok to introduce him to my 2 kids? How soon is too soon? The biological dad is completely out of the picture. He signed his rights away to the kids.

He is willing to meet the kids whenever I want him too but I'm not sure when is it too soon? I wouldn't mind him meeting them to see how they all get along before pursuing the relationship.