Omg I do EXACTLY this!! I have close friends that will 'help' me speak if it gets bad by saying the word for me. If someone wants to finish my sentence and it's not meant maliciously please go ahead. Then miraculously I'm fluent after I can hear it said...madness. A very good work colleague of mine will also semi-introduce me as part of her intro at any business event. It's not undermining and it saves any apprehension from pre-introduction stuttering nerves.