Pre registration gst

Is there any provision, rules, section in the law for reference ?

If Bill has been raised before the Date of Registration,

Then how can you supposed to avail ITC.

What about your GSTN. How will you get GSTN before Registration, for mentioning it on Invoice.

As per CGST Act, a valid invoice for availing ITC is that which carry GSTN of Both Parties in case of Purchase.

As per my view, You should request your supplier for issue of new Invoice mentioning your GSTN.