I Am Not The Registered Keeper Of The Car
Your NIP is probably effective !
The 14 day rule only applies to getting the NIP to the person/company who is registered as the keeper at the DVLA. There is no time limit in relation to getting the NIP to anyone else.
If you are concerned that the first NIP was not sent to the registered keeper within the 14 days allowed then the safety camera partnership will often provide this information.
If it is a lease/company car then check with the company you lease it from.
If it has taken a long time to send the NIP to you, you may have difficulties working out who was driving at the time. A delay in getting the NIP to you may help strengthen a reasonable diligence defence if you are accused of failing to name the driver.