Well it's an old thread, but hopefully still helpful.
I think it depends largely on the strain when you can germinate fresh seeds. I self pollinated a Green Crack plant, that is: I treated one branch with Silver Thiosulfate to create male flowers and then pollinated with that resulting pollen a couple buds of the same plant. The result were several hundred seeds. A germination test right after harvest had 9 out of 10 seeds germinate within 24 hours. After that I pollinated an Auto Afghan with the same previous pollen. The result too were many nice looking tiger striped seeds, but none of the 10 seeds of the fresh pollination test popped. I will wait a couple month and then will report again the result.