I'd rather find out when the MC finds out so it doesn't sway my choices till after the fact and also those moments will hit harder. Knowing before hand just kind of ruins it having that insider information, where my conscience is going to be making the choices knowing Lies deceit and secrets are being kept from the MC when he and the player should be oblivious to it till the girls tell him the truth.
When they get to the other city in the East I stop hitting on Jacinta where I shouldn't know about her deceit and secrets about what his brother did to Charlotte. Same with what happened to Olivia also with lies and deceit. Charlotte might be the only one between the 3 of then that has actual brains pushing Olivia to tell the truth but I bet she doesn't take her own advice and never tells the MC what happened to her.