kwaigonegin
Colonel
For reference, ATB bomber program began in 1979, in 1981 the winning preliminrary design was chosen. it was detailed and worked on until 1989. when the first prototype flew.
So, realistically, if there was already a serious design proposal which got funding at the beginning of this year, it may be there won't be first flight until 2020.
I know you said for reference BUT you cannot compare aircraft development from the US and China. A lot of factors are involve in the lifecycle of any aircraft development. Some planes take longer some take less. Most times it has nothing to do with technical issues but rather political, finance etc.