Thank you for replying and apologies for my late reply. Yes, I was able to flagpole on a Saturday afternoon and they said that they’re open 24/7. I got stuck for three hours on the American side as they denied us entry even though we had valid US visas. However, they were very polite and friendly and kept apologising. On the Canadian side it hardly took them half an hour to process our PR. After that we went back to USA for dinner just to make sure that we weren’t inadmissible and they processed our entry into USA very fast. The American border service officers even suggested places where we could have dinner in the small neighbouring border town of Calais. Everything went smoothly and we entered back into Canada using our temporary resident visas.
So everyone’s information Saint Stephen border is open 24/7 and you can flagpole on weekends too