Hi there. Thanks for the good question.

The answer is "don't worry about it."

The chart above is very basic and simplified. You go in and out of REM randomly depending on many factors. Only through experimentation will you find the best time for you. However, the chart shared above can be used to show you the general idea of what you want to do. Look at the beginning of it, and notice the hour plus lag before REM starts. Then, notice that the REM phases get longer through the night. The graph may be very general, but it shares those ideas very well.

You will not be able to time your WILDs or even WBTB DILD by a chart. What you should do is keep track of when you wake up in the night. Was it after five hours that you woke up feeling like you had just been dreaming? In general set it for 4.5 or more hours, up to 7 and experiment. Most of us have good luck after 7 if we can get back to sleep. I like to sleep late, so that works great. I can wake after 7 hours, and then sleep for 2 more.

Again, understand the principle and don't worry about minutes.