What happened in the United Kingdom is impressive. The government reached the 0.7% target while the country was in the midst of the global financial crisis of 2008. The government maintained its objective. That tells me that there is never a good time to define the 0.7% target. We have to set the objective and have a plan to achieve it. It is always a good time to do that.
On May 16th, 2017. See this statement in context.