One thing to bear in mind, most domestic ADSL will have a pretty slow upstream connection. So your *handwave* 10Mbps down might only be 1Mbps up.
500Gb is 4,000,000Mbits, ie, will take 4 million seconds to upload.
4000000 / 3600 = 1111 hours = 46 days to make your initial upload.
Obviously, subsequent syncs will be change data and much faster, and if you have to restore it (using my example figures) it’ll “only” be 4.6 days for the recovery which may well be fine for home use.
Of course, faster or slower ‘net connections it will vary accordingly, it’s probably a non-issue on cable / fibre and a showstopper if you’ve got a shonky connection.