Since you are already planning on getting married: if you get married before you submit, you substantially reduce the risk of a technicality or shortage of documentation (again, from the perspective of the visa officer) resulting in your application getting rejected for not meeting the common law test.
You can always have the larger wedding ceremony afterwards (esp since not known when covid restrictions will be lifted). If there are religious issues, most/many religions will allow for a 'blessing of union' event.
Note we can say 'civil marriage' and you can have a separate civil ceremony, but in Canada most religious weddings are combined civil/religious, with the officiant 'deputised' by government to conduct the civil marriage - that's the part where witnesses sign the marriage docs.
At any rate if religion is a factor, speak to the people at your religious institution. I'm sure in covid time they will attempt to be accommodating.
Not pushing, but I don't see why you would not get married before submitting app if you're planning to get married anyways.
