'ROLLING'
I was never taught at an A/G field one should do anything other than check all is clear then call 'Ready for Departure' and then take-off. You should not need to say 'taking-off' or 'rolling' because you checked the final approach path right?
Reference to CAP 413 says for A/G one may call 'Airborne' Which to be frank if I'm coming down final is far more useful than 'rolling' which just tells me what I already know, someone is on the runway ahead and therefore it is a wasted call, it doesn't matter to me if they are rolling or not, what matters is they are not still on the runway when I get there, confirmed by 'airborne'.