pencil something in
(pencil in a date, pencil in a time): arrange or predict something tentatively. This does not necessarily involve in the use of an actual pencil - the idea is that it can be erased.
A:Mary is planning to pencil in a group outing on the first week of May.
B:Let me check my schedule.
A:I hope you can make it.
B:I can't promise.
Refs
- English Idioms Facebook page
idiom, 14-04-13 21:20, 14-04-15 16:39, Marz
14-06-25 19:25, hasty rose bughaw