Opening the book…
The best day to start was years ago; the second best is today. People wait for more income, more knowledge, a better moment, and the waiting itself is the costly mistake, because the one ingredient investing needs most is time, and time is the one thing you cannot buy back later. A modest amount started now usually beats a larger amount started in five years, because the early money compounds the longest. You do not need to be rich, certain, or an expert to begin. You need to begin.
Start with whatever you can, even if it feels too small to matter, and automate it so it continues. Use tax-advantaged accounts first where you have them, and an employer match, if offered, is simply part of your pay, so claim all of it. Then increase the amount as your income grows. Do not wait until you understand everything. You will learn far more by starting small and paying attention than by reading for another year on the sidelines. Momentum, not the opening amount, is what you are really after.
Before investing for the long term, secure the basics: a starter emergency fund and a plan for any high-interest debt. Money you will need within a few years does not belong in investments that can drop, so starting now applies to long-term money, not next year's rent or down payment.