Never take a cold shower again! (unless you want to)

I decided to create a solution for the shower problem discussed below.
Is there a way for the water in your shower to come out hot/warm or at least take 15-20 seconds to warm up at the most? My design is the concept of an alarm type of system that you can set the time and the temperature to have hot water immediately in the shower.

My idea is to conserve water and reduce wait time...so in doing a little bit of research I have to find out what heats water and how it works. A hot water heater obviously heats the water. How it works:

The thermostat controls the temperature of the water inside the tank. Normally you can set the temperature between 120 and 180 degrees Fahrenheit (49 to 82 degrees Celsius). It is generally recommended that you keep the temperature between 120 to 140 degrees F (49 to 60 C) -- especially if there are children living in the house -- to prevent scalding. It also saves energy.

Normally, the thermostat is underneath a cover plate and it has a knob or a screw that you can use to set the temperature.
A water heater uses nothing more than the "heat rises" principle to separate hot water from cold water in the tank.

As cold water comes in, it remains at the bottom of the tank because it is denser than hot water. If you use the hot water faster than the heating elements can heat the incoming cold water, and if you consume all of the hot water that the tank holds, you run out of hot water in the middle of your shower. If this seems to happen too often, it could mean that the bottom heating element in an electric water heater has burned out or that your water heater is too small for your house. Or it could mean that you are taking really, really long showers. (http://home.howstuffworks.com/water-heater2.htm)

So then why isn't the water hot to start with in the shower when there is already hot water in the hot water heater? Reason being is because the distance from the hot water heater to the shower is a ways away and the water standing in the pipes before the hot water gets pumped to the shower head is cooled from sitting after previous use.

A device already designed works in this way:
You start it and not have to worry about coming back to the shower in time to shut it off. This prevents any additional waste of warm water that comes out. Thus it seems there will be more warm water available for taking a shower with.

But it still wastes water!

After conducting said research, I propose a thermostat system that will warm the cool water standing in your pipes at a time you set prior to showering, so when the hot water from the heater actually reaches the shower you will already have completed the first few minutes of your shower. Thus this will save water and I assume will utilize the same amount of energy (if the pipe heating system can connect to the same hot water heater heating components).