If your Key field in the "people" table is a "user" field, it will make this easy down the road.
If you don't have it already, create a relationship between the People table and the Time table. Each Person has many time entries.
The "Related Person" is going to be the key field (i.e. The User field)
then on the time table you can change the reference field from a "User" field to a "Formula-User" field.
Then just have the formula be [Record Owner], this will automatically connect the time entry to the user/person that created the record.
There are a few other things to consider here when setting this up, so if you have more details I can help clarify and make any clarifications needed.
