I'd like to make the Work Order date earlier but I can't seem to pick the date that I want.

We do allow deliverable start dates in the past, but they must be on or after the start date of the current/active Master Contract.

The deliverable start date can't be before the start of the master contract. so you will want to be intentional as you set your MC start dates.

If you need to Work Order start date to be on a specific date in the past, make sure your Master Contract starts on or before that date. You can send a new invite to your Vendor with updated Master Contract dates, which will then change the allowable WO start date.