Peonies from seed is not like other perennial seeds which flower the same year or following year.They need three months warm period to root then eight to twelve weeks or more in cold to sprout a leaf.At best you are looking at a minimum of three or more year to getting your first flower and 8-10 years before plant is mature.Your best bet is to mail order from one of the better peony growers.The American Peony Society website has a link page which list the best vendors,Adelmans,Hollingsworth,HiddenSprings,Klhem's and a few others.Also make sure you have a period of cold weather,they need winter dormancy.Fall is the perfect time to plant peonies.