Unfortunately I don't know the answer to your question, but if you're concerned about the time it's taking I will say that after you get one full backup the subsequent backups only back up anything that changed, so it goes much faster. Of course, if you're worried about disk space, then that won't help much😉
That said, though, backups of some sort are always a good idea. You never know when something bad will happen and you'll wish you had one.