Clones not showing roots after a week

Now, I wouldn't be surprised if I just need to wait a little longer, but I figure it doesn't hurt to ask. Is it normal for none of my 18 clones to be showing roots after 7 days?

They were all taken from the bottom 3rd of my last plants, ranging in height from maybe 4"-12". A few are turning yellow but most at least look healthy. They are sitting in a covered clone tray with the humidity doors opened under 5 normal CFL lights. Sprayed 1-2x daily. They stems were dipped in clonex about 1/2" before placed in rockwool, soaked in ph 5.5 water. The light gets turned off at night but perhaps they need 100% darkness?

as long as its pretty dark it shouldnt be the issue all i did for mine was filled up a few bottles with water and popped them in there took about a week and they both had only a few roots but i planted in soil and they took no problem

Some take two weeks, mine took a week n a half with just water

5 days is the quickest I've had roots. 7 days is great. I've spent 3 weeks rooting some strains.