If you have something exceptional in common, he has to notice that, and contact you first.
The rare exception we have found is when a woman “beats a guy to the punch” by answering his ad first and later finds out that he was about to answer hers, but hadn’t gotten around to it. Avi: Should a woman view a man’s online profile anonymously?
(Do not refer to it by saying something like, “oh, you said you like the Knicks, so do I”!
) Also, she shouldn’t add him to her favorite’s list as that is a dead giveaway of interest. If you don’t call back, a guy will try again by calling, texting, emailing, or Instant Messaging you.
But don’t reprimand him for not calling sooner by saying, “If you had called earlier…” Just say, “Really, I’d love to, but I can’t”.