Hey mate, good luck on the transfer!
I wouldn't try to map out your hours or anything, the beauty of the PhD is that it is up to you. In other words, work as much as you feel you both need to and want to, not because you think you need or should do a set amount of hours a day/week.
Just take it as it comes and you always need to factor in youtube/facebook time it is just apart of your working life, just see it as time to drink your coffee and get warmed up :)
Finally, you will have days when you work amazingly well and days when you don't, just don't let them get you down, put each day behind you and move on.