This is true, the more you know the more you will probably earn. This isn't a fast rule, but if you know you are doing usually do a better job. With mutual funds, I wouldn't recommend waiting if you have the money to invest now. The thing about mutual funds is that you are choosing stocks, bonds, or other investments that are in the fund you want.
When you are investing in stocks, you should make sure you know how to choose stocks, because this has a huge impact on how much you can earn. The same goes with bonds and other investments. With mutual funds, the only thing you are choosing is the actual fund. If you are worried about choosing the wrong fund, go with an index mutual fund because they are going to be the same. They are basically funds are invested in the stocks that are within the index such as the S&P 500 or the Dow Jones industrial average.
I would recommend investing money right away if you have the money. As I said, put an index fund. As you learn more you may decide that there is another funny you would prefer, then you can move it. But most likely, you will earn more money in index mutual fund than you would in a savings account.