Ovulation coming up

hope

One app says I should ovulate today, this app says tuesday, took this ovulation test this morning, could I still ovulate tuesday or is it more likely going to be later than that. The line is sooo faint! My donor is supposed to come down tuesday, so I'm hoping I can catch my ovulation. I know there's no way to tell when it'll happen but it's so faint I feel like it may be later than Tuesday?