I don't remember exactly how long it took, but I do recall it was a significant amount of time, like maybe two weeks.
And the device needs to be on during all that time?
Yes, it's a node, which means that it needs to download the entire blockchain. This requires time and internet. If you turn it off, you will be able to continue from where you had stopped, provided that you had it turn off gracefully and not forcefully (which may damage the files you download). The time that the device is turned off, it won't download data, so you can consider it like a "pause" of the syncing process.