Few options here once you get ITA (where your status is still single):
Calculate your CRS score together with your spouse. If the CRS score is still above the invited CRS cut off you can,
a) Get married, Inform IRCC of your change in marital status, add your spouse to your application and submit the application together
OR
b) If your CRS score falls below the cut off, Submit your application first and get the e-APR . After that get married and then inform IRCC of your change.
Reason is if you submit before e-APR, your CRS score gets recalcuated, but after e-APR, it remains the same.
More detailed discussions here: (unable to post links yet. you can copy paste into a new tab
canadavisa.com/canada-immigration-discussion-board/discussion-related-to-getting-married-and-submitting-spouse-docs-after-eapr-t412176.0.html