Story progression

I am close to finishing the first scene in this bar now. I had a feeling for how to progress with the story, but I only decide about what exactly is going to happen at the moment that I have to make the corresponding image. Now I am making a series of images with variations in posing and expression during a dialogue.

I know some suggest to make a full script first for the main story line, but I think I might get bored making the graphics if I already have the whole story. I do know the general direction in which the story has to go and I know some major events that will happen, but everything else is improvisation.