For anyone reading about time-related problems in these comments, I have a thought before you begin following this guide: you don’t need to disconnect the battery.

I have done 2.5” hard drive replacements like this on 13” and 15” MBPs dozens of times and never once disconnected the battery for this simple operation. I always use an anti-static mat to work on and am very careful about static electricity; but overall I would say for these types of Macs where the HD is such an easy swap, there is demonstrably no need to disconnect the battery, at least in my experience.

Glad you were able to figure out the Terminal time reset, Kevin.

Finally, with the power and data cables disconnected and the display held up at around 80º, you will find that the adhesive along the bottom edge of the display assembly will take quite some work to free. As the guide says, you can use a plastic card; but I found it necessary to use a metal spuger (carefully so as not to touch the power supply board of course!) in order to free the lower adhesive and remove the display.

Overall, take your time and focus on "being one with the iMac" as you work, and you will find it quite trivial to remove this 27" retina display.

If you cut around the display well and take your time to roll back and forth (using the iFixit roller opener tool), especially around the corners, you don't actually need to use any cards (Steps 9 - 17) to get the screen to come free of the body. On the top edge left and right, take each end of the screen gently and pry free with your fingers - GENTLY - and you will hear the remaining tape separating along the sides. Take care NOT to flex the screen as you do so.

If you are removing a cracked screen (as I was), be super careful to pry and swing the display EVENLY up from the body - this is an item of utmost importance, whether you use cards or not to get the last of the adhesive to release.