Revalidation of ca final registration????

Can we revalidate before expiry of registration, or do we have to wait until expiry. My regn. is valid till December,2017. Should I revalidate it now or wait till December?

Hi My initial registration will expire on Nov 1st 2017. Am i supposed to get my CA final revalidation done before applying for the exam form? As on the date of filing the exam form my registration is valid and also, while filling the online exam form for it does ask for revalidation date but it is not marked with an asterix.

Please answer at the earliest.

Thanks.