Generally speaking kit manufacturers, especially kit an kilo manufacturers, are concerned with selling more and more kits NOT with the brewer making the best beer possible. They know that if they say in the instructions to wait, they may loose some people to hobbies that have more instant gratification.
They also know that the time that a homebrewer will remain buying kits is relatively short...they know that after a few kits, the brewer will either give up, start brewing extract batches from recipes in books and places like this, formulate their own recipes, or go all grain...so they want to sell as many kits as possible to the new brewer before he moves on to bigger and better things.
SO they no that even their beer will taste better if you leave it longer...but they know that in the time you wait you will be reading and learning and be less likely to buy another kit...They can sell three or four kits to you if you follow
their directions in the same time frame that listening to us and waiting a month and bottle conditioning for another 3-4 weeks.
Most of us wait 3-4 weeks and skip secondary...but if you choose to secondary you should wait til your
Hydrometer tells you fermentation is complete.
Usually on the 7th day you take a hydro reading, and again on the 10th day, if the reading is the same, then you can rack it...
If I do secondary (which is only when I am adding fruit or oak) I wait 14 days then rack for another 2 weeks...then I bottle.
But that's only if I am dry hopping or adding oak or fruit, whicnh I rarely do, so for me it's a month than bottle,
Honestly you will find your beer will be the best if you ignore the kit instructions, and don't rush it.
But Even Palmer says you should wait with kits...
How To Brew said:
Leaving an ale beer in the primary fermentor for a total of 2-3 weeks (instead of just the one week most canned kits recommend), will provide time for the conditioning reactions and improve the beer. This extra time will also let more sediment settle out before bottling, resulting in a clearer beer and easier pouring. And, three weeks in the primary fermentor is usually not enough time for off-flavors to occur.
Your beer will thank you for waiting....