I now have nor have I ever seen any evidence to support germinating your seeds outside of your grow medium. It's just plain craziness that's gone around forever. How many seeds have I germinated directly in soil or rockwool...I dunno anymore, way too many to count. How many have ever NOT germinated.....0
I see threads all of the time about people who germinate their seeds outside in a paper towel or in a some water, etc. and then plant and bam there's a problem. Seed won't poke, tap root wasn't facing down, I may have touched the delicate taproot, just plant the damn thing and move on.
Grab a cup with solid sides, fill it with soil, plant the seeds, add water and wait.
Rockwool isn't going to help you or make your plant grow any stronger or faster, just plant it in the soil.