Downloading would be about 4-5 hours for me on PC and 8-12 hours on PS4. For some reason downloads on PS4 are rather slow.
I did order a physical copy for PC tough through bol.com since it's €10 cheaper then steam, free delivery on release day. I'm not that obsessed with diving in at midnight, I did that with Witcher 3 and it messed up my sleep cycle for weeks. (one does get older...)