Nothing Odd About This.
For the Japanese, odd numbers are considered lucky, so today is the day when proud parents celebrate their girls aged 3 & 7 or boys aged 3 & 5. I wrote about 七五三 (shichi-go-san/7-5-3) last year and did a pretty good job of it, I must say.
Not much to add except that I learned that this tradition dates back to the Heian Period (794-1185) and that November 15th is a particularly auspicious day, thus good for celebrating kids' growth. Prior to the age of 3, children's heads were kept shaven and after age 3, they were allowed to let their hair grow out. (They have since stopped this practice.)
I spoke with a co-worker who's daughter is approaching her third birthday and she tells me that she'll be waiting a year to buy her daughter's first kimono, for she's too short right now to walk comfortably. Several other families have also opted for this and some will be waiting until the 7th birthday for a kimono and just use formal dresswear for this year.
I have to go buy some 千年飴 (Chitose-ame) or 1000-year candy tonight. I hope it isn't too stale.