"optional notes" or "cue notes"

I'm writing out a part that has lots of rests at the beginning. To assist the performer in keeping track of where they are in the music, I was going to add some small noteheads with some text to help with that. It's the same notehead idea as when the part could be doubled, but doesn't need to be, but if you want to, the notes are there and available.

Where can I find these smaller noteheads, or what can I do to make these smaller noteheads?