Mine started swelling at about 15 or 16 weeks. So it's pretty typical I think. At first I would elevate my legs, but then that didn't really work unless I spent hours a day doing it, which I couldn't.
I ended up buying support knee hi stockings. In the US I had to get a prescription so they would be covered by insurance. At first I wore them 3x a week. Then every day. They REALLY REALLY helped and actually felt good. I'd wear them during the day and of course remove them at night. They also come in colors black, navy blue, or that wonderful beige color (blech) so you can wear them to work (if you work). The knee his worked for me, but some women wear support stockings instead.
PS You need to drink WAY more than 2 Liters of water. Whatever the equivalent of 2 gallons is the right amount. I agree read Dr. Luke's book follow the guidelines, but don't stress about eating as much as she says. It's pretty difficult. It's the amount of protein that's critical. Good luck!