Sleep Wave Training - Help!

Ok moms...I haven't posted very much on here but now I'm in desperate need of some advice and support. My Emma is 5mo today and was sleeping through the night by about 3 months. She definitely regressed around 4mo and we haven't really figured it all back out because her 4th month was so packed with travel and family that we knew her typically consistent routine would be all out of whack. My hubby and I decided that today is the day to start the Sleep Wave method from the Happy Sleeper book (basically put them down awake/drowsy and check on them every 5min if they cry but NO touching/soothing) and I wanted to see if anyone else on here has had success? I just got done attempting her first nap and was horrified at how upset she got. I'm almost too guilty and sad to admit she cried so hard she threw up before I finally picked her up. I did the every 5min check in for 45min (as suggested) before stopping. The book says it's harder to start with naps than bedtime but wanted to get a few real opinions before continuing this approach for the next few days.