。
I should have just stayed home from the beginning.
Literal
Rather from-the-start home [to-に] existed [direction-方が] was-good.
いっそのこと 'might as well / if anything / rather' signals a preference for the simpler/more drastic option. 初めから 'from the start / all along.' ~方がよかった '(doing X) would have been better' is the past-tense comparative regret construction. A straightforward expression of regret.