A year or so lost in your 20s is nothing
That's moot! If I had started my RAF career a year or two earlier, I would have been in a different demographic cohort with markedly different (faster & higher) promotion opportunities.
How my abilities/deficiences would have influenced my career is a different question, but I know for sure I wasted 2 significant years (63 and 64) by not being in the rat-race already!