Yes, for privately owned vehicles, the rules state data must be on the MID within 7 days of a policy starting, or 7 days from a change being made to a policy. 

For commercial fleet-type policies or motor trade policies it is different.  In these cases the data must be on the MID within 14 days of a policy starting or within 14 days of a change being made on the policy.

MIB monitors these targets very closely for every insurance company and they all strive to ensure they exceed these targets so as to avoid any disruption to their policyholders.