I've had my 04 Prius for just six months now, but I only have 3200 miles on it (I live just 4 miles from work). Should I take it in for service now or wait until 5000 miles?
Manufacturer recommends 5000 miles, but depending on your personal perference or belief, you change change your oil every 3k. It doesn't hurt to change the oil more often. Also, if you are swapping out the oil for synthetic, then go for it.
If you don't take it in now, and if something fails later, Toyota may argue that you voided the warranty. (I feel the same urge to wait, but my caution tells me to do it now.)