Hi Emanuel,
That's an impossible question to answer, because it depends on things outside of UpdraftPlus. Especially, it depends upon a) the amount of resources your web hosting company has + allocates to your site, and b) what other processes are running on the server at the same time.
The only way to find out is via testing.
Subsequent backups will be similar in time taken, because UpdraftPlus takes a full backup each time. It doesn't yet have an incremental mode.
David
