There are several instances of "Ten Commandments" in the Pentateuch (Ex.20:1, Ex.34:28, Deut.4:13, Deut.10:4), so the term was used ever since they were given. I have no doubt that early new testament Christians would have continued that use.

That the RC ten are different than the Protestant ten I knew; that the Jewish ten were different, I had not heard before. That is a good question.

Meta4

There is no such thing as preaching Christ and Him crucified, unless we preach what nowadays is called Calvinism. It is a nickname to call it Calvinism; Calvinism is the gospel, and nothing else. - C.H. Spurgeon