My dd is five months and we have got rid of her dummy over the last two weeks, doing what a friend did with her lo. When dd was tired I used to bounce her in her chair and give her the dummy to wind down. So I did the same but didn't give her the dummy unless she got really upset. And even then i took it out after 10secs or so. Over a few days she got used to winding down without the dummy, so then I put her in the cot when her eyes were really drooping and she was so tired by then she didn't care there was no dummy!
The next step was to start putting her down at the grizzly stage and letting her fuss in her cot until she fell asleep. If she started to cry properly, I'd go in and comfort her (still no dummy though!) but if not, would let her grizzle on and off for 5 mins before going in, stroking her, kissing her head and telling her it was okay. Then left for another 5 mins. I found it helped to turn her onto her side facing away from me if i had to go back in so I wasn't distracting her - then roll her back onto her back before leaving.
If she woke up half way through a nap, I would go straight in, roll her onto her side, stroke her hair, kiss her and tell her it was okay then leave for five mins. She would usually grizzle for a minute then drop off. After a few days she stopped waking up half way through naps so I started doing the same at night. She's slept through the last three nights now - she didn't usually do it before so i think it has really helped.
I guess I never realised that a small amount of grizzling is okay (1st time Mum!) - she would fuss in her bouncy chair or on my shoulder and that was fine but if she did it in her cot i would panic and go cuddle her. It really helped me to realise that a bit of fussing on her own was fine and there was a difference between that and a proper upset cry.
Sorry for the detailed post but hth! Think five months is good time to get rid of it - they're old enough to learn to get themselves back to sleep but young enough to break habits fairly quickly. Take it one step at a time - and best of luck!