Did you set up some escrow to hold the funds for this campaign OP because @Royse777 is right because there's a possibility that you will run away from the funds and there has been a lot of cases in this forum where the manager has run away and didn't pay their participants.
No, as I said before, money is sent in advance. There's only a select few that "require" escrow but most participants understand if I am sending first payment before the ad starts they aren't being scammed.