If you have to wait by the shower with your hand feeling the water temperature for minutes until it gets hot, or if you don't get enough hot water for what you need, you want to call a plumber. Stop wasting money and see what is wrong with your water heater. Every time you let the water run, you are wasting money and wasting water. There are a few different issues that could be causing your hot water to be delayed, or that could explain why you don't have enough.
The location of the hot water tank could be the reason you have to wait so long for hot water. If the home builders put the hot water tank on one side of the home, the time that it takes for the water to get to the other side could be annoying, and the water may be cooling by the time it reaches its destination.
The problem could be as easy as having a plumber move the hot water tank location, if they can add new gas lines safely. A new tankless option could also be a solution to the problem.
Have the hot water heater flushed and cleaned to see if this fixes the delayed hot water problem you're having. If there is a build-up of minerals along the sides of the hot water tank, and there is corrosion and other problems in the pipes, this could be affecting the hot water supply. The plumber will also look for safety problems with the gas lines and electrical components.
If the tank is flushed there will be more room for water storage, helping to increase your hot water supply.
A traditional water heater could need replacing as early as 6 years after installation. If the tank is getting over a decade old and the components don't work as well as they used to, you may need to replace the unit. You'll want to consider replacing the unit with a new tankless water heater that works efficiently, and that provides all the hot water you need on demand.
You are wasting your money if you have to turn on the shower and walk out for a few minutes while you wait for the water to get comfortable enough to hop in, and you want to get your water heater examined by a plumber such as one from Plumb Perfect Plumbers. See if you can make your water heating needs more efficiently, and consider replacing the unit if needed.