〜ばよかった

If that was the case, you should have told me earlier (implying regret)

I should have done it this way from the beginning.

If that's the case, you should have told me earlier.

I should have done it like this from the very beginning.

I now regret—belatedly—that I should have asked from the beginning.

I wish you had told me earlier

If only I had done this from the beginning.

(I) regret not having said it (when I had the chance).