One of the ways that Jirav can build a revenue forecast is using quota bearing headcount; in order to learn how to create this type of forecast please refer to the help article Quota Based Revenue Forecasting.
In order for the forecast to build correctly you first need to indicate which staff are in fact quota bearing.
To do this go to Plans->Staffing and scroll down to the
From the screen shot above note that in the table the right most column is "Quota Bearing"
By selecting the check box you indicate to Jirav that this staff, Evan Wells in this case, is quota bearing and their hire date is Jan. 1, 2019 which is when their sales ramp will being, please refer to the help article Quota Based Revenue Forecasting for additional information.