Here are some email templates for later use you can use to initiate contact with your mentees. You can use these templates if you'd like, or you can come up with your own emails.
"Hello, my name is [your name], and I'm excited to be your mentor for CodeDay Labs this summer! I wanted to reach out to schedule our first meeting, here are the times I'm available:"
"Thanks for meeting with me! Now that we've discussed a little bit about our project, here is what I hope you can get done this week."
"Hey there, I was hoping we could meet for thirty minutes to talk about the project and what you hope to do after CodeDay Labs ends. Here are the times I'm available."