For many years people have believed that piano is the best instrument to learn before embarking on the learning curve with any other instrument. Why is this:
1) Unlike guitar and other instruments piano is laid out in a "linear" fashion that makes it easy to understand theory
If one can play piano, they could quickly transfer that knowledge to other instruments
Do the above reasons however mean that piano is the best instrument to learn before any other? I would hazard to say "not necessarily".
Through the Spaulding Method of learning, each student learns to speak music natively like a second or first language. We learn the language through the context or dialect that inspires us:
In all truth there is no need to learn piano first if your desire is for guitar. The two instruments are quite different and offer very different benefits. Start on guitar if your desire is for guitar. Start on drums if your desire is drums. Don't concern yourself. All professional roads in music lead to the same end: Overlapping knowledge between all instruments. So when you follow your passions you will always get further.