Like most writers, I carry around a notebook for ideas, first drafts, Morning Pages, and the occasional class assignment. I bookmark my progress filling pages.
Later I edit and rework on the computer. A bookmark marks the next draft needing entry. If something leads me to enter drafts out of order, I simply mark it off with a check mark in the margin.
Austin Kleon and others advocate revisiting notebooks. When re-reading notebooks I have another bookmark.