I've been looking at GOG threads for their general release times and I'm generally seeing 6am PST or 9am EST.
Well 6am PST would be 4 hours earlier than Steam which would make me quite happy.
I've said it once and I'll say it again. I'm 36, I now have money but not enough time to use what I buy. So IF it's out earlier on GoG, Larian will get my cash a second time.
For just a 4-hour headstart? Wow.
For me it's about playing for a few hours on 3rd, then heading to bed at a time that's casual for me (9pm, then read until 11pm) and going on playing on the 4th xD
So yeah, I'd definitely pay 60 euros again for 4 hours of headstart.
But don't worry, I wouldn't spoil anyone or anything, just use that time to relax and such.