Why more confused? Usually when you get a call from a company they TELL you the signing is at XX o'clock - and usually no wiggle room; that's the time THEY have set with the borrowers/signers for YOU to go to them - without consulting you about your schedule first..
When a company requests your services at a time TBD - that means YOU have the control of setting what time you and the borrowers/signers can agree upon. The company has set the date (based on a number of other factors in the background) but the company is telling you to do it at a time YOU can accommodate.
As Arichter said - that's a YAY in our book.