Ask living relatives about the dates and places of births, marriages and deaths that they remember. Reminiscing about who attended memorable family events (weddings, funerals) will help pinpoint who was where, when.
Do not believe every date you hear, however. Although many people remember dates accurately, many more do not. Always try to find official records to verify your family's important dates.
Official sources such as birth and marriage records are usually accurate, but there are cases when they are not. For instance, travelling clergymen often baptized babies as they made their rounds in rural or remote areas of early Canada. Birth dates were therefore being recorded several months after the fact and, sometimes, you will find that a wrong date was supplied. In some cases and cultures, birth dates may not be as important as dates of related events, such as christenings or circumcisions. Be sure you have correctly identified the event to which a "birth" date corresponds.
For marriages, be sure what you have is a marriage date and not the date on which the banns or other prenuptial announcements were read. Several Canadian provinces required such announcements. Determine where your mother, grandmother and great-grandmother or their respective parents resided at the time of their marriage. It was customary to celebrate marriages at the residence of the bride or her parents.
Birth dates reported on death certificates and tombstones may not be reliable, especially in the case of elderly persons, where no one living may have known or remembered their exact birth dates.
With the passage of time, people can forget the year of their own immigration, the name of the ship on which they sailed, and the port at which they arrived. Finding passenger lists, immigration records, and naturalization records to verify dates of migration can be a challenge when details are forgotten or remembered incorrectly.
As with variant names, record all variant dates and sources. You will depend on dates to sort out discrepancies and develop accurate family timelines.