I searched the Irish Family History Foundation's online database at ROOTSIRELAND.IE. It has abt 20M B/M/D records for most Irish counties, including Sligo. Records before 1863 are increasingly sparse: almost non-existant before 1800. Protestant records are scarce for all dates.
For Wil(...) Kilwee B ?, somewhere in Ireland, with the parents' names unknown, I found 1 record in 1829, Co. Antrim. However, either the parents' forenames weren't recorded, or weren't John and Margaret. This record is most likely a false positive.
Suggest you visit the database, register (free), browse (free), and opt (also free) to be notified if more records are added. At this early date, your chances are slim.
My family line emigrated from Tipperary to Canada in 1833.