It is my understanding (please correct me if I am wrong) that a significant number of pilots are unsuccessful in their first attempt at the aircrew selection assessment. Often, second or even third attempts may be required, each a year apart. This, when combined with a decision to delay for a year before starting the process , and the relatively narrow age acceptance window the OP might want to consider whether the risk is worth the delay.
(When questioned regarding other alternatives to being an RAF pilot when he was beginning to approach the upper height limits, a close acquaintance fervently stated that he would cut his feet off first.
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"You have to want to fly so bad that you dream about it, talk about it, work very, very hard to get it, give up other things that are not directly relevant to it, take every opportunity to experience it. Anything less will be quickly identified as an indication of lack of commitment".
Good luck
Imagegear