Use the chart on the link above, but no one can really tell exacly when it will poop. Just watch it and if you see swirlys ... QUICK!! rush to the toilet buttin and you will see it on the toilet!
well you could try experimenting with your tama...say the last time your tama went to the toilet was at 2:00 and on the chart it says that your tama would go to the toilet again in another one hour...than at about 2:50-2:59 watch your tama for wave lines then you would toilet train it...or something like that.....