Unless you are 24/7 (which implies a power exchange which implies one of you is always dominant and the other always submissive...) then there are lots of opportunities for having such conversations.

And evenif you are 24/7, there are methods and modes for such conversations.

The most important differentiation between discussing needs and desires v. topping from the bottom, is whether or not you are actively within a scene.

Before? After? Those are the right times.

My girl and I are always talking. If not, how would I know the things she craves. Some of them have not come to fruition because (as the dom) I wasn't interested at that time. She must "live" with that. But she knows, because I've told her so, (anticipation is a great tool,) that next summer, she will be eating at my feet, because I've grown enamored with the idea of seeing her do so.

Seeds are planted. They take time to germinate, grow, and bloom.

Fortunately, she sowed a lot of seeds last summer.