OK I got a good natured MN roasting when I thought my hv's miscounting of weeks/months was the proper way!
So I may be being dim about this.
Basically my hv and Annabel Karmel book start out by saying wean at 6 months.
Then on the next page (Quick and easy weaning Kindle edition) Karmel is adamant baby MUST have her first solids no later than 24 weeks (or become a fussy eater and lack vitamins).
Well that isn't 6 months is it believe me I was told this many times on a past thread! Because that was the error my hv said doing an approximation ie 4 weeks = month!
So what's right? I just thought MN had sorted it out and it was wean at 6 months! 
If you search my history you'll find the embarrassing thread! 