Is it unacceptable if I message guy 10am and he responds to me the next day?

I had chatted with him on facebook everyday for 9 days straight.

(we weren’t friends before we started to talk regularly, we just chatted occasionally)

We don’t chat throughout the day. I usually reply to his late evening message in the day and he usually replies to my message in the evening after 9pm. His messages are sometimes lenghty (you can tell that he likes to talk) .
now he replied late to my message….
I still can’t tell if he’s interested….
Is it unacceptable if I message guy 10am and he responds to me the next day?
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