Sleep training - day 3 is worse than day 1?!?!

I am trying to help my son learn to self settle. I am using the Ferber Method in conjunction with shushing and patting as he is used to being rocked to sleep. Day one was difficult and he cried for almost 50 minutes then day two he settled in half the time. On the third day it got worse and went back to day one and he was protesting a lot. Is this common?? I am sleep training because my son wakes up every hour after 12 am and I’m returning back to work soon please don’t judge me for trying to sleep train. Thank you!