Meeting The Kids. HELP?!

So my guy has a 6 year old and a 3 year old. We've been together for almost a month and recently the topic of meeting his kids came up because my mom wanted to take him and his kiddos along with us to see Monster Trucks in January. It sounds like he wants me to meet them before then and I'm nervous as hell. I know that it's a very sensitive thing for parents to introduce their SO to their kids and I don't want to cross any lines (especially since I'm quite maternal). Anyone have any suggestions?

**Not sure if this goes into love and sex given that it involves my relationship or the health and lifestyle so if it's the wrong one I'll repost in the right one**