Each evening I fill up 2x2 litre bottles from the tap and put them in my fridge. before I go to bed I decant some into a 750ml 'sports' bottle which I keep next to my bed. I try to drink most of that before I even get up. I then refill my sports bottle from the bigger one to take to work, and take the remains of the big one with me too. So I manage to consume 2 litres bhy the time I finish work, which is 2pm. I then come home and start on my second bottle.
I find this little routine is working quite well for me, I am managing my 4 litres plus shake fluid too. I do try not to drink too much late evening as I need to wee in the night if I have too much, and find it hard to get back to sleep if I wake up.