Request primary assignment entry date use for cycle time calculations
I've been asked to create a request report that captures the time from the request entry date to the first user assignment date. Will the primary assignment entry date reliably return that date? My initial testing looks like this is a valid field for what I want to calculate, but I wanted to double check here.
I've reviewed the Tips and Tricks Calculated Fields https://experienceleague.adobe.com/en/docs/events/the-skill-exchange-recordings/workfront/apr2022/calculated-fields, and thought I could use the SLA section (around 8:15) in the video to create the entry date-first assignment calculation. But the video shows "User First Assigned" in the calculation and I'm not sure where that field comes from, since it's not a database field and if it's a calculated field, I missed how the field was created.

Thanks for any insights on this.
Cathy