Everytime you falling back asleep, you go through NREM before you reach REM. But what we can control is how long will the NREM be.

As we go to bed, first NREM is about 80 min long and REM is 10 min. This makes up one 90 min sleep cycle. The longer we sleep, NREM will become shorter and REM longer, untill maybe after 7-8 hrs of sleep, we go through just a very short NREM. That's why it's recommended to WILD after some hours of sleep, usually at least 4.5.

But even if NREM lasts let's say 20 min, it's not as bad as it sounds. First stages of NREM are falling asleep and light sleep. When we WILD, during these, we will swear that we are still awake, when in fact we are already asleep. So if you WILDing and thinking "man, this is taking too long, I'm still up", think again. Don't give up, continue, because you maybe already closer than you think.