Effective date for reverse charge method?

Dear Sir,

 

I have a doubt in respect of the Notification No. 15/2012 dated 17/03/2012 which deals with 10 Services which will be charged under Reverse charge mechanism.  As mentioned in the notification this will become effective only after when the Finance Bill become Finance Act.  Recently on 8th May the Finance bill has been proposed and approved in Lok Sabha but yet pending with Rajya Sabha. Will it become effective from the date of approval from Rajya Sabha or from what date? Kindly clarify...