Hello how about game if i dont start new game can i play blood and wine in my old save game ?? did someone test that?

Yes, you can load an existing save into Blood and Wine. Just load that specific save while the DLC is activated (in GOG) and downloaded, the corresponding quest automatically appears, similar to how Hearts of Stone did it. Be sure to be at least level 34, otherwise you will have a very hard time facing off against opponents up to level 70 (like that damn wraith that killed me in one hit)...