ECing with intervals is a way to understanding the frequency in which a baby pees. Sometimes, they don't communicate with a fuss or a squirm or the blank look or whatever, or mom/dad misses the cue. When Belle is busy playing, she will often not given an indication that she needs to pee, but I can use another clue to know that its time to put her on the potty.
I can know when she peed the last time.
Between 4-5 months, she was peeing every 20 minutes. I figured this out using an iPhone ap where I can record pees and poops and their times. Its designed for diapers but I use it instead to track eliminations, wherever they occur, in the potty or otherwise.
Around 6 months, the interval switched to every 40-45 minutes. Now I find that I need reminders or I get distracted or engaged in something else and I miss it. Using my iPod Touch, I set a timer to go off. This has been helping.
Its been fun choosing the timer sounds too, right now we've using the old car sound-- a horn that sounds like like "Oh-oooo-gah!" Sounds perfect for a poop sound!