Were Pre/Post-Dated Coins Produced In 2017?

Refer to official RCM Mint Reports for the dated coin you have in question, and one year of Reports either side of that.
The latest Charlton catalog may be of assistance.
If you are friendly with your LCS, they may look up that info for you, but just remember, you are using their time at no profit to them, so be courteous.

The latest obtainable mintage info is in official RCM Reports, and are open Public information and should be easily found with an on-line search. It is most probable that just for a few years before 2017, mintage numbers can be found in digital form.

For much earlier Reports published, mintage numbers are most probably in PDF form, which make getting to the mintage number information you require, is a much more tedious and time consuming problem.
Instead, refer to coin catalogs, such as Charlton.

Think of all the dealers and collectors who buy rolls of everything every year. You can be sure that most of the 2017's are being held by thousands of speculators who ordered rolls from the mint and think they will make a fortune. Shortly after they were released, there were many being offered on ebay at 10 times face value (and many already slabbed). It will be easier to find uncirculated ones in 20 years than circulated ones. This is like what happened to the 1967 nickels - you could hardly find any in circulation for years but now you can find hundreds of uncirculated ones for sale (I have a bunch still and can't get 50 cents for them). Lots of non-collectors hold onto these commemorative types of coins.

Clearly, yes, there are many of these still circulating, but at least from my experience over the past year (I'm in Ottawa) I don't get them frequently. Maybe 2 in the past year, and I pay cash for things (think Tim Horton's) near daily.

I see far more 1992, 1999, and 2000 commemorative quarters than 2017 coins of any denomination come up. The mintages of these years are in theory comparable compared to the other commemoratives, which have generally around 10,000,000 or less, with some exceptions. The 1992/99/2000 quarters have a total of hundred(s?) of millions per year, and supposedly the same with 2017. But I see probably 5-10x more of those old quarters come up, even with ARP having whittled those numbers down for the last while. As I've stated I have got around 2--not more than 3--2017 coins in the past year, of ANY denomination. Hence why I speculate there were probably pre/post dated coins in 2017--that, or there is extreme hoarding of these coins.