i think u shudn't delay.
at ur situation one should give an exam as early as possible.
but they have a month one rule. so stick to it. stick to it.
i am telling from my personal experience.
last year I got a 680 on march 27th. The best strategy was to give the exam within a month. But I delayed and it has been almost an year I haven't given the exam. Of course my needs and motivation level changed, but that can happen to anybody.
since u know it was a bad day, and all u need is to maintain ur preparation level, just go ahead. take a date. one monthe from now.