In the Quebec civil law system, wills and land transactions are normally handled by a notary, rather than a lawyer. In the rest of Canada, it is a lawyer who typically handles wills and land transactions.
The notary keeps a copy of all files, or greffes, as long as he/she practices. Upon retiring, the notary turns over the files to their successor. When a notary dies, the files are transferred to the courthouse. About 100 years later, the last record is transferred to an archive.
There are printed guides available at QFHS and the Bibliothèque et Archives nationales du Québec that list all notaries who have ever practised in Quebec, including the years they practised and the archival centre where their records have been deposited.
When searching for a notarial record, keep in mind that you may encounter three different county names: