Some clarifying observations about notice of changes coming into force:
Publication in the Gazette is the formal, official, and legally necessary notice. It is true that for many transitions in both statutory and regulatory law, the formal publication in the Gazette is the first public notice. However, there are many occasions in which the Gazette notice was published
after the date the changes actually took effect.
Perhaps the most salient example of this was the big change in procedure made by Bill C-24, eliminating an applicant's right of appeal if denied citizenship, and removing the Citizenship Judge's role in deciding all but residency or presence cases. Bill C-24 received Royal Assent in June, 2014. These procedural changes were dependent on when the Governor in Council ordered them to come into force. The Governor in Council's order was dated July 31, 2014, ordering these provisions to come into force on August 1, 2014, and this was not published in the Gazette until August 13, 2014.
(see Gazette Part II volume 148, No. 17, published on August 13, 2014 at
http://www.gazette.gc.ca/rp-pr/p2/2014/2014-08-13/html/si-tr71-eng.php )
That is, those big changes were part of Bill C-24, which received Royal Assent June 19, 2014. On July 31, 2014 the Governor in Council ordered these changes to take effect the very next day, August 1, 2014, but there was no publication of this in the Gazette until two weeks later, August 13, 2014. In the meantime, if CIC (this was before it became IRCC) gave any public notice these profound changes took effect any earlier than the Gazette, it was low profile and not noticed by many, including many of us closely following the implementation of Bill C-24.
In contrast, however, CIC and IRCC have typically given notice of many transitions before the formal, official publication in the Gazette.
Here too, provisions in Bill C-24 are an illustrative example. It was June 4, 2015 when the Governor in Council ordered the 4/6 presence rule changes to come into force as of June 11, 2015. This was not published in the Gazette, Part II, until June 17, 2015, in volume 149, No. 12.
http://www.gazette.gc.ca/rp-pr/p2/2015/2015-06-17/html/si-tr46-eng.php
As I recall, it was Friday June 5, 2015, and late in the day, that CIC posted notice that the new rules would come into force June 11, 2015, in effect giving no more than one business day notice in time for a prospective applicant to send off an application by overnight courier so that it would arrive at CIC by Wednesday June 10, the very last day CIC would accept and process an application made under the 3/4 residency rules. It was virtually, practically, no advance notice at all.
Harper's CIC had many reasons for delaying notice of this particular change. As far as I can discern there are not comparable reasons for the current government to delay giving notice as to when the 3/5 rules will take effect. Thus, I'd anticipate a full week's notice, at the very, very least, but proably more like a few to several weeks notice.
But I would NOT anticipate notice in the Gazette first. Rather, I would expect IRCC to publish the information in a public notice or at the least prominently posted at the website.
Obviously, if for example one anticipates that IRCC will give at least four weeks notice of the changes, which is a reasonable expectation, as of now it does not appear the change will take effect before a date in November. And at the very soonest, allowing for significantly less advance notice, not until later October anyway.
Here's the thing: this is almost certainly going to happen this year, and happen before the December holidays. Not that far off. Time flies. No reason to sit on the edge of one's seat or keyboard anxiously watching for news. It is coming, coming rather soon at this juncture. And there is no doubt, once notice is given, the forum will explode with posts spreading the news. Only those hiding under a rock will not be aware what the date will be.
As I have noted elsewhere, the actual date is not all that critical for those who are waiting for the changes in order to apply under the new, lower threshold of presence requirement. Anxieties aside, a few weeks one way or the other is not likely to make a huge difference in most PRs' lives. The vagaries of processing times will have a bigger effect.
The prospective applicants who really have something at stake in this, in anticipating the date the changes take effect, are those who are now (or soon will be) qualified under the current law but who do not yet have a safe margin over the minimum. They have real motivation to apply before the changes take effect. While, perhaps,
beating-the-rush will not make a big difference, the odds are likely that those who apply
beating-the-rush will be processed first and at least somewhat more quickly, to potentially a lot more quickly. So of course many of those in this situation, balancing
beating-the-rush versus building a comfortable and safe margin, have good reason to be paying close and careful attention, looking for news of when the date will be.
Everyone else really can and should chill a bit or a lot.