If you want to germinate from seed but using ebb/flow what medium do you use?

[thinkerr]

if you are starting a new grow from seed what medium do you put the seed in until it has established roots?

can you wet paper towel germinate then put the sprout in a diy cloner and wait for roots to develop then transplant to ebb/flow (hydroton)?

can you put it in seedling rockwool? but then do you need block rockwool when you put it in the ebb/flow buckets? or can you leave it in the seedling rock wool?