Hi Ya, They advise you to add manure to heavy clay soil in autumn. I have sandy soil so tend to add mine in the spring. As digeroo says you can add it any time and it's never to late. Some crops do not like fresh manure, i.e. carrots, as this causes forking. A good book that will help you on your way, and I use mine even now, is Dr Hessayon's vegetable expert, well worth the investment. Every thing else will benefit and if you are on new ground you may not know when the last manure was added. If using animal manure make sure it is well rotted especially horse manure as I mad the mistake of putting it on direct and even now after 5 years am still battling grass seeds from it. It is said that it needs 6 months to rot down. Horses don't digest grass seed as well as cattle. Also get your compost heaps going and I add fresh horse manure to my helps to rot them and help build up heat in the bin. Good luck and enjoy the success's as well as the failures that we all suffer even after 20 years of veggie gardening. I really enjoy my plot and feel the pressure of life lifting as I open the gate. Happy Gardening