I read somewhere about fresh seeds to but cant remember exactly why u dont want to plant right away. Wait at least 2-3 weeks and store them in a nice dry place until ur ready to plant, however i do remeber reading that u will have better luck with seeds that arent so new.
I germed some 10 days after harvest, but felt lucky when they opened. They were quite mature on the plant, though. Waiting 2 weeks or longer is usually much more successful in my experience