Initial backup restarting after end of day shutdown

I am attempting a full disk backup on my work laptop to a shared NAS. The initial backup will take more than 10 hours and my workday is 8, so at the end of the day, I shutdown and take my computer home. The next morning, I restart the backup, hoping to have 2 hours left, but it appears that the backup is starting at the beginning again and I have another 10 hours to go.

Shouldn't the backup continue on from the stopping point?