Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Investing in low cost index fund — does the timing matter?
If you're worried about investing all at once, you can deploy your starting chunk of cash gradually by investing a bit of it each month, quarter, etc. (dollar-cost averaging).  The financial merits and demerits of this have been debated, but it is unlikely to lose you a lot of money, and if it has the psychological benefit of inducing you to invest, it can be worth it even if it results in slightly less-than-optimal gains. More generally, you are right with what you say at the end of your question: in the long run, when you start won't matter, as long as you continue to invest regularly.  The Boglehead-style index-fund-based theory is basically that, yes, you might save money by investing at certain times, but in practice it's almost impossible to know when those times are, so the better choice is to just keep investing no matter what.  If you do this, you will eventually invest at high and low points, so the ups and downs will be moderated. Also, note that from this perspective, your example of investing in 2007 is incorrect.  It's true that a person who put money in 2007, and then sat back and did nothing, would have barely broken even by now.  But a person who started to invest in 2007, and continued to invest throughout the economic downturn, would in fact reap substantial rewards due to continued investing throughout the post-2007 lows.  (Happily, I speak from experience on this point!)