One would expect that the baptism date of a child would be on or most likely after the birth date. Not what you will find always in these records in Ireland after State Records began in 1864 and indeed up to the early 1900′s.
It was normal in that era that a Catholic child was baptised within a day or two of being born and indeed if the birth was early then the baptism may take place that day. It is not uncommon to find a significant difference between a birth date on the State Register and the Baptism date in the Church Baptism Register. The baptism date could predate the birth date on the State Record by several weeks. One notes in the State record that the birth was often registered several weeks after the stated birth date. I tend to take the baptism date as being the more reliable. The child, Timothy on http://bmdnotices.com/remembrance…/viewremembrance.aspx… has a baptism date of 23 Aug 1868 and a birth date on the State Register as 17 Oct 1868.