529 Plan -- Need in Fourish Years

[iwasjustwondering]

I have two children, in 8th and 6th grades, and I could use some advice.  I am planning to invest around $20K per kid into their 529 plans each year, over the next few years, until they are done with college.

Because the older one will be going to school soon (first tuition payment is usually due in winter of the senior year, right?), how should I invest the money?  Should some of it be in a cash investment trust, or bonds?  Put it in the mutual fund set up for each of their graduation years (this is where I currently have their college funds). 

Should I keep some of the money out of their 529 plans? If so, where?

If it makes any difference, I will be putting around $10k per kid into their accounts at one go, in March, and about a thousand per kid into their accounts each month starting this month.

[Another Reader]

You don't need it all in 4 years.  For the first kid you will need it in 4 to 7 years and for the second kid in 6 to 9 years.  That should make a difference in how you invest.  You would probably want safe places to cover the first two years for the first kid, with some type of ladder structure for both kids in years 6 through 9.