I plan on working this job from the mid May to the end of May.
"5月の中旬から下旬にかけてその仕事をする予定です"
I plan on working this job from the mid May to the end of May.
I plan on working there for about half a month starting mid May.
there = 仕事場
...working at XXX でもいいです。
I intend to do this job from the middle of May to the end of May.
少し変だと思いますけど、これで通じます。