I've never known officials to be too concerned about when the checks take place. But I've also never heard a complaint. So I'd suggest asking the host school administration, or coach to handle it, or visit with the officials, about your concern. If the host school says skin checks will happen at 8:45 I don't think you'll get any grief from the officials.

Mr. Cue makes a good point too. If you do checks earlier a kid can run down to a local clinic and perhaps find a doctor that will examine the condition. But here's my take on skin conditions. Its not fair to other wrestlers to let an infected wrestler spread his crud to others. The coach sees the kid every day, and should know whether the kid or team has health issues. Take care of them before Saturday morning so the official isn't put in the position of being a dermatologist. My pet peeve is when I raise a kid's hand and I can tell he's got a fever--but he wants to wrestle so he risks infecting 100 other kids...and me.