He kept saying he was going to start working, but he never actually started.
このシチュエーションでの「何度も来ると言っていつも来ない」は
ーHe kept saying he was going to start working, but he never actually started.
のように表現できると思います。
例：
A guy we hired kept saying he would start the next month, but when the time came each month he just put us off again, so we had to let him go because he was too focused on his main job.
「雇った男性は来月から働き始めると言い続けたが、毎月その時がくると言い逃れをされた。彼は本業を優先しすぎたので、辞めさせた」
to put someone off で「人から言い逃れをする・言い抜ける」
to let one go で「人を解雇する」
ご参考まで！
カナダ 
