This is what it says on the back of my big brand named cactus mix seed packet:
SOW: Scater lightly in pots or trays of seed raising mix, firm down and moisten, keep in warm place. Some seeds may take months to germinate.
CARE: Can be potted individually when large enough to handle (carefully) but most spectacular when grown together in a large container. Like all plants, cactus benefit from applications of a big brand soluble fertiliser. Protect from snails.
That's word for word...
Other than Sow late winter to early summer (subtropical to tropical region), depth 2-3mm, germination 4 - 12 weeks, plant space - enmasse.
Personally I don't know if that has helped - it's for various species that's all I can tell you.
Pictured on the front are various mammaliria, opuntia, even astros! But god only knows what is in the 0.2g (approx) of seed!