don't mean to correct you or anything, just trying to look out, but i believe the correct pH to buffer rockwool is 5.5 (and i've heard lower), although some rockwool cubes/slabs come pre-buffered to be pH neutral without needing to condition it

and honestly, i've always had 100% success rate with the paper towel method, and usually most germinate in 12 hours. If the glass of water works for you and always has, then definitely keep doing that, im just saying that it works for me

but i would definitely wait till you have a taproots before you plop them in the rockwool

*edit*
also, the soaking is for 24 hours @ 5.5 pH