If I'm going to a spoken exam (or making a speech, phonecall etc), instead of making a script word-by-word, I'll approach the situation with a general idea of what to say instead and improvise. If I rely too much on a script, it will fall apart fast when I start stuttering. Especially if I have to substitute entire sentences. Here's a different routine I do: I stutter more when I have to raise my voice or yell to reach whoever I am talking to (usually someone who says hello from a distance), so I'll wave and walk into normal distance first before talking.