I think you must have meant the new moon huh? Tinctures are supposed to be started on the new moon and harvested or pressed on the full moon.
Yesterday the 2nd was the new moon according to my calendar but I'd say if you're tincturing tonight it'll be okay. It's best if we start on the new moon but a tincture started a day late is better than no tincture and all I say!
I think it would be fine to add the herb you're missing tomorrow, I've done that myself. Since we're making the tincture for our personal use we usually leave it tincturing longer and the longer it tinctures the stronger it gets YAY!