NEW YORK ( TheStreet) -- All over the country, high school seniors are putting on caps and gowns and heading across the stage for that cherished diploma. Next comes college -- and a tricky set of payment issues for students and their parents. Many families that have worked hard to save for college now have money in multiple pots -- cash in bank savings, 529 plans, a variety of stock and bond mutual funds. Which accounts should be tapped first, and which left for later? It's hard to know for certain because you can't predict investment returns over the next few years and don't know how much college costs will rise. If stocks soar, it obviously would pay to leave money in stocks and stock mutual funds for as long as possible. But stocks are risky, and you could suffer a big loss if the funds for senior year were kept in stocks and there was a downturn at the last minute. College savings are needed at a specific time and are spent over a short period, making it very hard to wait out a slump. Retirement savers, in contrast, have more flexibility. They can postpone retirement, trim their budget or work part time to recover from an investing setback. So it's probably best to hedge your bets with college money and not get too greedy hoping for whopping returns. Consider, for example, how the pros do it. Mutual fund firms that offer target-date funds for college savings put most the money into stocks when college is years and years off, then switch to short-term bonds and cash as freshman year approaches. On the other hand, the stock market has been doing well. If you can handle some risk, stocks holdings could grow nicely over the next two or three years.