Transitioning cosleeping to crib at 4 months via cry it out

My only child turned 4 months on Saturday. For the first 3 months of her life I could not get her to sleep anywhere but on me. That's really not much of an exaggeration. There were times that I'd be up for more than 12 hours at night just trying to lay her down in her crib, pack and play, heck any flat surface at all to sleep on. The only way she'd sleep was nursing on a boppy. I tried moving her when she was drowsy but not asleep, when she was in light sleep, deep sleep, half an hour into a deep sleep, everything. And when she did wake up, there was no telling if it would take minutes or hours to get her to go back to sleep on me. I would say that I successfully managed to get her to sleep somewhere other than on me no more than 10 times in three months. This includes daytime naps. And I was sleeping .5-3 hours per 24 hour period. I know a lot of people are advocates of cosleeping, but it is something that I never wanted to do. At 3 months, I finally gave in and we started cosleeping because the risks seemed substantially low considering all the times that I fell asleep holding her. So now it's a month later. I had tried a few times to put her in her crib and return every time she first cries, but it very quickly got to the point where I wasn't even making it two feet from the crib before she was screaming. I put her in the crib during the day sometimes to look at her toys and be familiar with it, and we do the standard night time routine. We only recently have her taking real daytime naps thanks to her fisher price swing. Her pediatrician encouraged us to use the cry it out method. I personally prefer to try to correct her sleeping habits before they become more ingrained and even harder to correct and am aware that there is disagreement between whether the earliest to start CIO is 4 or 6 months, but they also say a 4 month old should be perfectly capable of sleeping in a crib. I tried it last night, and it broke me far worse than I had expected. I let her cry a few minutes before coming in to soothe her, and she started crying as soon as I had left. Seemed pretty standard. Then her screaming got to a whole new level. I waited five minutes and came in but could not console her. At all. I finally picked her up (as far as I know I wasn't suppose to) and it took more than 15 minutes to get her to stop screaming even holding her. She was still very upset for another half hour. I did not put her back in the crib. Has anyone else used cry it out to sleep train a 4 month old? How bad was it at first? Did it work in the end? Also, if the only comment you can make is "you should never use cry it out ever/at 4 months" without at least giving an alternative suggestion, just please don't. It isn't helpful.TL;DR: I'm desperate. Has anyone else used cry it out to sleep train a 4 month old? via /r/Parenting http://ift.tt/2udZdPr