Answer: Tell her a new requirement could mean it'll take you 2-3 weeks to clear applicants for hire . . . and then tell her like this:
Email: It may soon take us 2-3 weeks to clear applicants for hire.
HR reply: 2-3 weeks or 2-3 days? It takes you 1 day now.
Response: 2-3 weeks.
HR reply: That's a major problem.
Response (wait for it, wait for it): Out of my control.
HR Manager is seething. Can you get why? Yes, the absolute lack of ownership, responsibility, and understanding portrayed in the four words, "out of my control." It's really not the possible 2-3 week delay because no HR Manager worth her weight in gold is going to let anyone or anything add 2-3 weeks to her hiring process - and that's a given.
Holy smokes folks, don't communicate this way. Just don't. Get it or move on. We've got things to do and you are only in the way.