Contraceptive Patch

I plan on having sex on friday as I'm meeting my long distance boyfriend and that's the only day we'll be able to be physical with each other. So i ordered patches as soon as I realised that however I only started them on Monday. I'm in the luteal part of my phase and this app predicts I should start my period next week (though usually I'm a few days later than this app predicts/possibly even a week at times as I have irregular periods- unfortunately sometimes I even start sooner). Due to this, people have told me I wont be protected from pregnancy until the week after (so the following Monday), does this mean I wont be protected with the patch at all on Friday? Or will it just be less effective?

I don't want to risk getting pregnant but me and my boyfriend really wanna do this as we won't be able to meet often.