<prompt> Human: I decided today that I wanted to open up a Roth IRA. Bear in mind that I am a complete finance newbie and have basically no idea what Im doing, only that Im 28 and I decided I need to take my retirement seriously. I dont think at this point Ill be able to invest a full 5k annually, Im hoping to put 2.5k to 3k annually. Does it matter if you put that amount in gradually, or all at once? Is it better to invest the money at a certain time of year, or any other info I should know on that?I was also wanting to know how one determines the return percentage rates? Im calculating at 7 but I dont know if thats right, or even exactly how to figure that out. Edit for more info: My wife and I are very frugal people, and we dont care to retire rich. Weve talked at length about having enough retirement to live in a nice RV and travel from park to park every couple of years or so. Unless I am being completely naive, I feel like 400k would be quite enough for us. I know some folks aim for clearing a mil with IRAs but I dont care to aim quite as high, nor can I afford to at this point. In short, whats the best way to approach this? Im happy to provide any financial info I can.  <response>: Does it matter if you put that amount in gradually, or all at once? Either is fine and perfectly allowable. In general, the earlier you put your money in, the more time it has to growI was also wanting to know how one determines the return percentage rates? Im calculating at 7 but I dont know if thats right, or even exactly how to figure that out.Over multiple decades, the stock market returns about 6.9 after adjusting for inflation and including dividends. Source any given year it could go up 20, down 15, or not do much of anything at all. My wife and I are very frugal people, and we dont care to retire rich. Weve talked at length about having enough retirement to live in a nice RV and travel from park to park every couple of years or so. Unless I am being completely naive, I feel like 400k would be quite enough for us.A good guideline for the size of your portfolio to retire comfortably is 25X you expected annual expenses in retirement. So if you expect to spend less than 16k each year in retirement, 400k may be ok for you. 