If you get the booster earlier than recommended before your initial shots are losing sufficient efficacy your protection will not last as long as it should. You will be over-
protected short term which is unnecessary it will have worn off before it would have been most helpful/useful.
So don't rush right out and push yourself ahead of others and have to be the first. You will be shooting yourself in the foot. If you got your shot in December sure go ahead. But if you got it in April what are you nuts?