Clarity on one year time frame-cenvat credit finance bill 20

Finance Bill 2015 enhances cenvat credit time frame from existing 6 months to 1 year. My query is that if Invoice is dated 01 May 2014, could we take cenvat credit by 30 April 2015. OR all Tax Invoice should be dated post April 2015. Is there any clarification issued by Dept in earlier years? Please guide me.

Thanks & Regards,

Jayanta