Is it bad to have sex during the first date?

A friend of mine invited me to her house tomorrow and asked out of "curiosity" that if I believe in sex at first date. At least for me, knowing her a little bit, I feel this is a hint that she is interested in having sex with me tomorrow or in the future. In my opinion, im not ready to date anyone, i am attracted to her physically, but im not ready to have a date in terms of building a relationship. What can I say to her?
Is it bad to have sex during the first date?
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