...Best to cut some in anyways. Usually whats supplied out of the bag isn't near enough to give aeration for growing the ganga
Your gettin some good advice by some good guys here.
Well actually.... Coco once fully saturated with 20% runoff remains with a 23% air value just on its own.
But
Personally I like a finer grade of coco but I still mix about 20% perlite into it.
However for starting seeds I like plain coco as you can see from the picture. Any perlite on the coco surface of the plant showing roots is simply from back filling around the cup.
The pot awaiting it has about 25% perlite.
The perlite and rocks that the OP has in his may hinder some root development but shouldn't matter too much.
I think that the course mix that you've bought IMO should be used for larger plants on the next pot up after germination and a finer grade would benefit your next batch of seedlings.
Just an FYI you can clone in straight coco too.
Keep humidity high and you shouldn't see any yellowing of the clones either as they root.
J