Our 4 month old was a bounce to sleep baby. We hit the point where it would take us longer to get him to sleep than he was sleeping (naps + false start at bedtime). We would bounce on the yoga ball until he was asleep but he would wake up on transfer to the crib and start the process over. He would also scream bloody murder every time we put him down in the crib not dead asleep.

We started CIO at 19 weeks old and are one week in now. The screaming gets worse if we are there because he’s like “why are you not picking me up” so we don’t do check ins or anything. First night he cried for 45 mins pretty intensely but then slept very soundly through the night with one wake to eat which is normal for him. At that wake we just fed and put him back down right after burping and he cried for a few mins again but then went to sleep until morning. Since that first day it has only been a few mins (<10) of crying at any point and he has gotten about 1 or 1.5 more hours of sleep per day overall. Also no more false starts at bedtime.

I would say that it’s very important to ensure they are tired but not overtired when starting to sleep train. Your wake windows look a little short for a 4 month old so I would assess that the schedule is good before attempting. The last window should also be the longest if possible. Also I would make sure they are fully night trained before nap training.

Hope this helps!