for the (Agrobacterium) transformation you need to have transcriptionally active cells. Moreiver, transfromation process require at least 36 hours, durimg which embryos will germinate. I am not sure you can trynsform dry seeds.. How you lant to select transfromed cells, because you will never got all cells transfromed.. Good luck!
I agree with Taras. You can predict good result if transform single cells and get plant developed from one single transformed cell. Even if you transform all cells in embryo/seed (this is possible only in theory), the plant will be a mix (chimera) of different transformation events