Many years ago, when the IRA amount was $3000 per year, I divided that by 12, and set up automatic investments for $250 the first of every month.
In doing my studying for my fledgling tax business, I discovered that is called dollar-cost averaging, and it leads you to buy more shares when the price is lower, and fewer shares when the price is high. As long as the investment ends up, you've usually done better than if you're trying to time the markets.
Armed with this new knowledge, I went to my dad, and asked him (very hautily), why HE didn't dollar cost average!!!
"Oh, I do son...every January 1st".
It took a while, but when the light bulb finally went on, I realized he was waaaaay ahead of the rest of us. He figured out he'd only have to come up with the maximum ONE TIME, max out in January, then go back to saving $250 a month, so he'd be able to max out NEXT January. Meanwhile, the February investment had lost any gains from January, and the gains on those gains into perpetuity. March, I'd missed two more months. April, three MORE months, etc.
Then I asked myself: What is this, writ large? So I tracked twins: He maxes out on January 1st; she maxes out on the last day, April 15th of the following year. He starts at 20; she starts at either 21 or 22, depending on when the birthdays fall. But both make exactly the same money, and both put away exactly the same amount, according to the tax return.
Who has more money when they hit 70? Well, he does, of course. But HOW MUCH more?
Six figures.