Time to Start Potty Training?

I am not sure, but I think maybe it is time to start potty training. I went to the mailbox the other day and when I came back in the house Nick had his shirt up and was pulling at his dipar saying poop. Low and behold he had done just that. Is this an indication that he is ready for some potty time? We bought a potty a few weeks ago, but have not "forced" it on him yet. A lot of my family believe in going by the phases of the moon. Heck anything is worth a try. Lets hope this is easier than I have been told.