Installing Samsung EVO 860 SSD on Mid 2012 Macbook

I’ve decided to replace my hard drive on my mid 2012 MacBook Pro with a Samsung 860 EVO SSD. So far I have backed up the internal drive to Time Machine and fitted the Samsung SSD drive to a USB3 external disk case. I formatted the new drive as APFS, plugged it in and booted the MacBook Pro into recovery mode. It gave me the option to install Catalina to the SSD drive and it’s now running. It’s telling me this will take about 2.5 hours. Is this correct or do I have a problem.