For a turning Missed Approach, e.g. ILS DME Rwy 16L, the turn should not be commenced until reaching the published Missed Approach Point unless instructed by ATC. The use of the term ‘Mandatory’ with the turning altitude does not override this requirement.”
That was my understanding too until I did it in real life one day and had ATC getting excited about us not turning ASAP. We reported it but nothing was said subsequent.