I appreciate you may be holding out for March registration but the salesman may not be talking bs.
When I lived in England, I bought many a car month before registration as dealers were offering better discounts because so many people were holding on a few weeks to get the new registration. I preferred the discount as I have a private registration I put on every car so it was irrelevant!
If you suddenly were offered a car two months early it could be that it is not the car you were waiting on but another that has become free and the dealer is scrambling around to get it registered. If you don’t take it then he might discount it to someone else.