I take lecithin on my own for my nervous system but is expired is it going to work for me, how long does it take for me to feel better?

The benefit of lecithin for nervous system is still controversial and you also used an expired product so I do not think we can answer your question at all.

There is NO proven or established benefit from taking lecithin for "nervous system", and unclear if an expired preparation would possess any ongoing potency. Contact your doctor and discuss if taking lecithin is a good investment of your time and money.