Funnily enough I was just talking about that this morning, that it's really awkward having bonuses paid in March (informed end of Feb) just before the end of the tax year, because you don't know what your earnings will be until then, meaning you don't really know whether it will tip you over the thresholds for certain benefits etc, and hence e.g. you don't know how much to overpay your pension if you're not at the £60k/year limit yet. So it's like, e.g. you put enough in the pension to ensure you still get tax free childcare, but then if the bonus is bigger than expected it puts you over the threshold and you don't know about that until you've already made 11 out of 12 pension contributions and potentially missed the window to change it anyway.
Getting paid bonus end of April sounds ideal to me because then you have nearly a whole year to course-correct for the relevant tax year based on that, rather than just a couple of weeks.