take the initiative, if I had a r/l partner. I would like to think when it does happen and of course by me having control of who I choose for my partner that he would want me to an active submissive to help participate with all the rules of submission, like properly asking, and getting permission, and be an adversary to our relationship. Taking the responability (initiative) as the sub, because the Dom doesn't have a crystal ball and can't read my mind.
Now the Dom may of course may not like my timing and have to tell me that it is going to have to wait till later, but I would not be out of line for just asking if that is what I had my mind on.
I would hope my Dom would consider when I am to be at his beck and call, that if it wasn't approiate timing for me, I would be given some kind of heads up as that I would need to be prepared.
But all in all I think I would have a Dom that would want me to be verbose about my needs.
T