I shudder at this memory. Basically, I was an early developer, had my first period at eight years old! Anyway, I was in yr4 with a male teacher and it was hell, frankly.
I was forced to change in the dsiabled toilet because "i was more developed" and he didn't want the other kids to see that my breasts were developing etc. I was also banned from PE whenever I was "on" (my mum had to send a note in to say it had all started etc) and even though my mum said PE was fine this teacher was like, "no, you're not doing PE with your period. You can sit and read." Ugh that was awful.
So I personally think there's no issue until say, yr5, maybe. It depends on the kids really.