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'.
If you happen to visit Bagby we'd appreciate a 'Lining up 24 for immediate' call, as you can't be seen by anyone leaving the parking area to cross the runway to the taxyway. Then there's the small matter of aircraft using 24 for take-off and 06 for landing due to the slope.
I might just add that your 'Ready for departure' call is meaningless to an A/G operator. That's assuming the radio is manned. So 'lining up' and 'rolling' calls would be nice. Better than bent metal.