If you visit Vital Records of Charlotte County GenWeb at
http://www.rootsweb.com/~nbcharlo/vital.htm
you will see that there are no official records kept that early in the province, let alone the county or the parish. You will have to rely on census, family bible and church records.
Other provinces in Canada can be found at
http://www.archives.ca/02/02020202_e.html

There is no "town" St. David, it is a parish and covers a wide area. You will find more info, including a map of the parish at
http://www.rootsweb.com/~nbstdavi/
Good Luck