I used to work for USPS. Priority mail is great , first class or Parcel can truly suck. If we hard large loads of mail on any given day, we could defer our first class and Parcel post. Which means they would lay on the floor at our sorting station for a couple of days. First class and parcel post can be deferred for several days, seeing they have a 2-9 day delivery estimate. But for no reasons could you defer priority mail.. Thats why I ship all my items USPS Priority . 99% of the time they ship out at 9am the following day and should be to most everyone in 2 days, because I ship from the center of the USA. I will never ship first class ever ever ever.