As has been noted, there was an announcement to put out draft legislative proposals shortly, and then a commitment that, whatever effective date those proposals could take, it would not be before November 1, 2021. It's difficult to provide a timeline in terms of putting together a set of draft legislative proposals of this complexity.
I can speak to the general timeline for budget proposals, if that would be a helpful comparator. Often, in the federal budget, which is released in the spring, in March-April, the government will announce its proposed measures. For income tax measures it is common after the release of a budget announcement for there to be a summer release of draft legislative proposals. Those draft legislative proposals would go out for comment, often for a period of 60 days, before measures can be introduced into a fall budget bill.
While of course it's impossible to predict with any certainty the timeline for this measure, that's not an uncommon timeline for at least some budget measures, if that would be a useful comparison.