Well.. I started trying EC with DD when she was 3months, and wees were a rare catch, but she very quickly learned to deliberately poo when I held her on her potty.
I caught a poo everyday, however sometimes would miss an unexpected additional poo. She didn't seem to mind pooing in her nappy/sitting in poo at all.
Then we had some sleep issues so I stopped EC for a while, I was way too tired, and since the break, we've struggled to catch poos at all (though I haven't really tried much and also I don't know her timing anymore)
I'm confident that if I really tried diligently for a week, we could easily get back on track with catching poos.
DD is currently 5.5 months.
Hope this helps!