If you are putting something or someone on your schedule or to-do list with the knowledge that it may change later, you can say you will pencil it in.
You can use "it" to specify an event and "you" if you are talking to the person you are making the plans with.
Here are some examples of how to use this phrase:
- Let's pencil in some names of potential candidates, and if they don't want to do it, we can ask other people.
- Okay, I've penciled it in for April 20th. We can change the date later if anything comes up.
In a conversation, it would look like this:
A: I'm not available on Monday, but I'm free Tuesday afternoon.
B: Sounds like a plan. I'll pencil you in for 2 PM on Tuesday.
You can also learn more phrases for making and rescheduling appointments in Lesson 2.2 (Setting up a meeting: Executive invitations) of our Business English for Consultants course and our other Business English courses.