YOU SAID:

I never thought id see the day that arriving late to the party was a good thing

INTO JAPANESE

私は党に遅れて到着することは良いことだった

BACK INTO ENGLISH

It was a good thing for me to arrive late for the party

INTO JAPANESE

私がパーティーに遅れて到着するのは良いことでした

BACK INTO ENGLISH

It was a good thing for me to arrive late for the party