I am not sure if 'pre-hydrating' is a valid term to use for this, please correct me if you know the term.

While walking down a tiring route, I was so tired and low on water. All I could think of was, "ahh, I wish I had more water with me". I was carrying enough (for me), but a girl whom I met on the way wasn't, so I shared. When I reached a village after slogging for hours, sipping some after a typical interval and distance, I rested for a few minutes and drank a lot of water.

If I know that I am going to be trekking over the weekend, does it help if say from Thursday, I start drinking more water than I usually do?

This clicks my mind because I spend the whole day in air-conditioned office, so, naturally and unfortunately I drink less water than I am supposed to.