Greetings, caitlyn217!
Thanks for reaching out to the Apple Support Communities! That’s a great question you have about the time frame to complete the transfer of data from one device to another using Quick Start. The time frame can depend on different factors, such as connection method, signal strength, and interference. Check out this article to Use Quick Start to transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch:
"Quick Start occupies both devices, so make sure that you choose a time when you won't need to use your current device for several minutes."
Have a terrific day!