Hello Noathaimoumb13
Welcome to the SBB Community.
Question: when you book a flight for 24 June, can you still take the same flight on 26 June because you have not used the ticket? The answer is no, as the ticket is no longer valid.
Same with the Swiss Travel Pass continuous: when you have chosen the STP to start on 24 June, it will start on 24 June. If you want to start it on 26 June, you have to cancel it and repurchase.
Now, since the travel pass is already active (it is 24 June 05:33 AM here in Switzerland right now), I suggest to immediately call SBB to stop the STP: +41 51 225 78 56.
Kind regards,
Roland