The starting point is at curriculum design and development stage - "creativity" must be at the table to embed itself in the final shape and form of the curriculum being developed.
It may not be expressed as an explicit learning objective - rather it is infused in the subject curriculum delivery. Teacher professional development must, then, provide the skills to encourage, to consistently elicit creative responses and to positively recognise and validate the creative dimension in students' work.
Creativity should never be assessed in isolation - it may be identified as an element within the wider review/ assessment process.