(Need Advice) Freelancer Took 10 Hours to Reply to My Email

Hello, I'm not a professional recruiter so I would appreciate your advice.

I'm currently leading a research project and I had to hire four translators for the project (one document that will take a few days to complete). When I approved the proposal of this freelancer, she was quick to confirm her acceptance of the job. I then told her that I will be sending the contract shortly. I emailed her with the contract and asked her to affix her signature once she's through reviewing it, or if she has any queries, she can contact me. She did not acknowledge the email. I also sent her a DM informing her that I already sent the contract. As for the other translators, it just took them a few hours to review, sign, and send back the contract.

In the late afternoon, I messaged her again, telling her to please confirm with me if she's proceeding with the project up to a specified time. Still, no reply on the deadline, so I decided to hire another translator. A few hours later (10 hours since I sent the email), she told me that she's accepting the job.

Now I still feel bad about this because what else is worse than receiving an offer then having it retracted, right? It was a difficult decision to make, but her unresponsiveness also made me quite afraid that she might be unresponsive once we start with the project. But what do you think about what I did, is this standard practice?

Thank you so much in advance for your advice :)

Edited: to better explain the nature of the project.