Baptism USUALLY took place within a few days to a few weeks after birth (usually dependent on when the mother was sufficiently recovered and when they could get to the parish church). However, if the family was too financially distressed to provide the "donation," this period might extend to months.
Spelling in Ireland was highly fluid. Most surnames have several aliases. There are 81 accepted variants of the name "Breene." Spelling hardly mattered to the priest as most of his parishoners were illiterate, at least until later in the 19th century.
The baptism date of 29/04/1850 is well within the realm of possibility. It is highly likely that this record is for your ancestor; I would say a 99%+ chance. I suggest you go with it.