How many days from result i need to register for articleship

Hi ! I have cleared my Ipcc group 1 in this may. But for articlehip I m waiting for reply from good firm. CAN ANY ONE TELL ME WITHIN HOW MANY DAYS FROM RESULT(8TH MAY) I HAVE TO REGISTER FOR ARTICLESHIP. SO AS I WONT POSTPONED MY FINAL ATTEMPT. AND Whether articleship counted from date of deed&form or date of registration of articleship? PLLLS HELP