How long do they have to issue a warrant after drug raid?

The question states "anonymous tip." Unless the informant is already a "proven" source, an investigation, possibly involving the infiltration of undercover personnel into the location, will have to be made. The police MUST be able to show "probable cause to believe" that an actual drug operation is being conducted there, and an "anonymous" tip made by a person of unknown reliability is NOT sufficient cause to request a warrant.

THEREFORE: The answer to the question is unknowable - it may take time for the investigation and evidence-gathering to take place.