Mobile:
Go to Work Orders tab
Select Work Order to assign Start Date
Click Edit in top right corner
Click Set in Due Date & Repeatability field
Select Due Date
After selecting Due Date, add Start Date
Click Add start date
Select number of days from dropdown menu (from 1-30 days before Due Date)
Click Done in top right corner
Click Update
Web:
Go to Work Orders tab
Select Work Order to assign Start Date
Click Edit in top right corner
In Due Date & Repeatability field, choose Due Date
After selecting Due Date, add Start Date
Click Add start date
Select from preset dates (from 1-30 days before Due Date)
Click Update at bottom of Work Order