I search Irishgenealogy.ie, a new, FREE, online database of surviving Dublin City church B/M/D records. I found the following:
Marriage of WILLIAM LAWLOR of N/R and SARAH PURRESS of N/R on Date unclear Parish/Church/Congregation - ST. JAMES Area - DUBLIN (COI) Husband Wife Name WILLIAM LAWLOR SARAH PURRESS Address N/R N/R Occupation N/R N/R Father N/R N/R N/R N/R Mother N/R N/R N/R N/R Further details in the record
Baptism of WILLIAM LALOR of N/R on N/R December 1804 Parish/Church/Congregation - ST. JAMES Area - DUBLIN (RC) Name WILLIAM LALOR Address N/R Father LAURENCE LALOR Mother JANE LAFFAN Further details in the recordSponsor 1 GEORGE STEEL Sponsor 2 CATHERINE STEEL
There are several William Lalor B rcds in this database. This is the one which best fits your imputed timeline.