Hi.
You're not getting a lot of responses, so I hope this will be of some help.
Have you got access to a library? My main source of information is "The History of the Universe", David H Lyth, publisher: Springer, 2016
It's a short book which (in my opinion) is suitable for post-graduates in a rush. It describes all the required effects of inflation on pages 71~73. However, it's in the Appendix on page 102 where some criteria for the end of inflation are established. So the whole lot is no more than 4 or 5 pages of A5 size... or 10 minutes reading (and in my case, twice as long figuring out what was going on with your own pencil and paper).
I could repeat what is said there but I can't do it any better than the original text. I read it at speed and wasn't really concerned about this aspect anyway.
Assuming I understood the text, Lyth presents criteria on V'' that mark the end of inflation.
Best Wishes.
LATE EDITING: According to the info on the back of the book, the book is appropriate for the general public EXCEPT the appendix (the thing is without the appendix you've got nothing much except some nice words anyway).