Always disconnect power to the disposal at your home's circuit breaker before touching any wires or plumbing. This prevents electrical shock and injury. Verify the power is off by trying to turn on the disposal switch or a nearby kitchen light before you begin work.

The specified tools are highly recommended for ease and effectiveness. Channellock pliers provide a strong grip for stubborn P-trap nuts, and an adjustable wrench is crucial for securing the mounting ring firmly. While you might manage with other tools, these will make the job much smoother, especially for a beginner.

The most common mistake is not properly sealing the sink flange or tightening connections sufficiently. Ensure you use a generous roll of plumber's putty around the sink flange before installation. After the unit is installed and connected, fill the sink with water and check thoroughly for any drips or leaks around all connections before restoring full power.

Three hours is a reasonable estimate for a beginner, assuming you have all tools and materials ready and experience no unexpected issues. Your first time might take longer as you familiarize yourself with the process. Allocating an extra hour or two allows for troubleshooting without feeling rushed.