This is a little trick I learned after having trouble with another site of ours that simply was not getting crawled at the volume and rates as other similar sites as well as our pages not getting indexed fast enough after we published a post.
The issue was that pages would sometimes take three weeks to naturally be indexed by Google.
To check if a page is indexed and when it was indexed simply run the following search query into Google “site:yourdomain.com” (leaving out the quotation marks). What you will encounter is a list of pages that Google has indexed for you.
Now the best part, simply click on search tools –> any time. Now you can make a selection of indexed pages / posts for all time, past hour, past 24 hours, week, month and year (custom rage is also possible).
With this sort of filtering you are quickly able to check if say a post you posted last week was indexed and when. Hope this helps.