It states "I will make", not that it is already made.
He said he would make it and he did. That happened at the cross. This is very basic doctrine.
Mat_26:28 For this is my blood of
the new covenant, which is shed for many for the remission of sins.
Mar_14:24 And he said unto them, This is my blood of
the new covenant, which is shed for many.
Luk_22:20 Likewise also the cup after supper, saying, This cup is
the new covenant in my blood, which is shed for you.
1Co_11:25 After the same manner also he took the cup, when he had supped, saying, This cup is
the new covenant in my blood: this do ye, as oft as ye drink it, in remembrance of me.
2Co_3:6 Who also hath made us able ministers of
the new covenant; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.