Hmm, has she always been pooing every 3/4 days? Or is that just a recent thing?
I would be a bit concerned, tbh. But you say on your other thread that she's starting to smile at you. Is she sleeping more or less over time? Does she have some alert periods in the day?
Did your breastfeed your other two? If you did, your supply is likely to be better, and your new baby could be a very efficient pooer ...
The rare poos do have me worried, though, tbh.