The answer is No. Children should be encouraged to speak and dance in Child Drama from the very beginning. They will speak in their own language - but clarity is important. And very interesting this can be. Often it has wonderful imaginative ideas and sometimes true poetic content.
Teachers have to develop an ear for hearing and appreciating it.
But there can be more formal training apart from this. It can sometimes be done in Child Drama too. Everything depends on the purpose of the lesson. If you want to release imagination and personal expression, you allow it full rein and don't correct. It was quite wrong to think that one was modern if only creative writing was used and hopelessly old fashioned if you ever corrected other things.