1830: the only way to search for baptism records (births were not recorded) is to go through the church records: avail on microfilm from LDS.The only or major parish at the time was Notre-Dame de Montréal.The B-M-D are recorded chronogically in the church registry (as they occurred). If you are lucky there might be an index at the beginning of the year for B-M-D with a record or page ref.
If this birth had taken place prior to 1800, then it would have been a different story: the PRDH database is quite complete and accurate. Keep this in mind. PRDH is accessibleon line at a reasonable price if you do a lot of research.