as @Ed-and-Hugh0 indicated.. IB is only available to hosts/listings once there's a bit of history.
IB is primarily a convenience for guests to make sure that they can feel secure that they have a place to stay and that nothing bad will happen to the reservation. often new listsings have a higher rate of cancellation or host flakyness so IB has a delay period before you can set it.
if after 10 or so bookings it's not there you may want to contact CX and ask what the criteria is.
last year, about 1/3 of my bookings were from IB, so far this year more than half are ib. it's fantastic.