Potty fascination before 2 years old can be an early sign of toilet-training readiness -- but more often it just means your child's a curious kid who loves trying out new things. Occasionally it progresses to full potty training, but it's fine if the interest fades, says Erica Kates, M.D., a pediatrician in Ludlow, MA. Most kids this age simply aren't physically and emotionally ready.
For now, let him sit on the toilet if he wants, praise him (whether or not he goes), and show him how flushing works. But avoid pressuring him -- it'll only turn the potty into something un-fun. And you'll need all the help you can get next year.