You should be ok, 4grams in 24hrs is the top end of recommended dosage.
Your over that but not by much, and should be fine. Unless of course you already have decreased liver function, in which case call a doctor asap.
If you start to feel unwell or get stomach pain then go directly to hospital.
And dont do it again!lol everytime you overdose on the apap you do some damage to the liver and although the liver can take a fair battering it will eventually fail, sometimes without warning.
Remember, chronic apap overdose is as dangerous as acute.
Edit: its a little late for activated charcol. Its only useful while the drug/poison is still in the stomach...9hrs is more then enough time for the stomach to empty.