for those who had success with cry-it -out method

Nadia • Miami ,FL
At what age did you start ?
How long did it take to work ? 
Did you stop all night feeding at same time ?
My LO is 6 months and wakes up every hour or two ..it's the only way he can sleep is after nursing ..  he wakes up every 60-90 miniures , nurses for 20-30 minutes and goes straight to sleep 
I read the Ferber book and know what to do but I'm struggling with what to do with night feedings ? 
No judgement please , I've done everything and it's getting really hard to function without sleep For soo long . 
Thank you to advanced  !!