Just for the record...all babies sleep a 40 minute cycle...and you'll find the majority of babies cat nap during the day right up until they are around 6 months old. My daughter in now 6 months old and has just started solids and only now is being put on a specific routine which encourages her to sleep for more than 40 minutes. It did involve a little sooking (not control crying) but eventually she herself started to sleep longer...she now will usually take at least ONE 1.5 hour nap a day.. So don't fret if your 4 month old isn't napping for longer. AS for the dummy...I'm a fan and my daughter still has one for bed. It's usually not a problem at night (she puts herself back to sleep) and I only give her the dummy around 5-6am if she wakes which satisfies her until 7am when I get her out of bed for a feed.

So don't rush to get rid of the dummy..trust your baby will get rid of it when they are ready to and you are willing to. As for sleep school....I wouldn't worry about it unless your baby is NOT sleeping at all during the day. I can't recommend the following book enough as it saved my sanity...Sheyne Rowley's Dream Baby Guide. But it only is for babies from 6 months and onwards.