I don't have personal experience of Paph seed germination. It probably depends on species, but in P. wardii, germination started after 3 months or so (under the optimized condition).
Asymbiotic seed germination, seedling development and reintroduction of Paphiopedilum wardii Sumerh., an endangered terrestrial orchid
I think P668 is about 1/2 MS, so they used full strength P668 + some hormones. Darkness seems to enhance germination of many paph species. It appears that green pod method is better for this species (about 6 months after pollination), and if you let the fruit mature, seed dormancy develops in P. wardii.
BTW, if you search google scholar, you can get quite a lot of info about Paph seed germination.
slippertalk has lots of experienced people with paph asymbiotic propagation.