In what way did she send them?
Radak: She told them 'go in peace.'
Did she tie the thread now?
Radak: The verse records now that she tied it later, at the time that they conquered the city.
Malbim: Yes, she tied it immediately 1 , lest people sense [that she made a Siman with the spies] if she tie it later (at the time that they conquer the city).
Even though this was just after the spies left her house, now there was no reason to suspect her. She counseled the messengers how to catch the spies! After they chased and did not find them, there would be more reason to suspect her. (PF)