Depends what variety of Wisteria you've got - W. sinensis can take up to 7 years, but sometimes only 3 or 4 years. Wisteria floribunda varieties are often sold in flower, and usually flower at a much younger age, but the flower form is slightly different, tapering down to a long point.
The ground should be prepared by digging over and incorporating humus rich materials, such as composted animal manure or good garden compost. Subsequent feeding consists only of applying something like Growmore or Vitax around the base in spring, as growth begins, and turning or raking it into the soil.

I used Tomorite last year to feed my wisteria and after years of waiting for flowers I finally got buds this year, its always best to buy them in flower so you know that you hjave not bought a dud one.

I don't think there's such a thing as a dud one, Marion - if you want Wisteria sinensis, which takes longer to flower, you're unlikely to fnd one actually in flower. Doesn't mean its a dud though...

Hopefully you have a grafted plant and not one grown from a seed? Seedlings can take many years.

Sorry Bamboo, I meant grafted.