Question

Is there a way to know a date when a person worked on a lineage?

Answer 1

Absolutely; click on Changes in a profile to see the complete history of who did what, when. A lineage is a fuzzy concept; there's no way to look at more than a profile at a time (unless I've missed something!).

Answer 2

You can look at the Changes tab on a profile to see all of the activity on that profile. It shows who worked on the profile, when, and what changes were made.