you can buy galvanized sleeves you attach to the falsework or robertson decking.
various sizes are avaialble. they have a push out cap on top to keep them from
getting filled up with mud
holesaw thru the robertson decking before attaching the sleeve with tek screws.
i've seen people not do that, and have to cut the decking after the concrete is poured.
it's not as much fun that way.
that's the inexpensive part. laying out the deck correctly costs more.
edit: laying out the deck incorrectly costs even more than that.