I read where you can do it with some accuracy in the first few days before their fur comes in. It has to do with spacing between the anus and genetils. Wider space boy, shorter space girl. After the first few days when fur grows in its tougher, but then I have no practicial experience just research.
If you Scroll down to the first pics the first pic is a male (hane) 3 weeks, the second a female (Hona) 3 weeks. If you Scroll down further the first pic is a male (hane) 8 weeks and second female (hona) 8 weeks.
I hope this helps you On my baby rabbit i can see the differences when they're 3 weeks, a male has more space between anal and penis and it looks more together like amd 0 , while female keep the anal and vulva closer and the vulva looks like an I, but both come upp when you press hard.
But it shouldn't be so hard now when you got good close up pics