My 5 month old silkie rooster keeps mounting my 5 month old hen that isn’t even laying

[FarmShenanigans]

So I got 5 silkies they r all 5 months old. I have 3 roosters and 2 hens, the roos are all crowing but my hens aren’t laying yet. I witnessed one of them mounting my silkie hen but I already have 3 other hens that can lay (a black australorp, unknown breed and a leghorn) so why is he going for the hen that isn’t laying and is it normal?

 

[sourland]

She's smaller and easier than the big girls.

 

[BDutch]

She is probably almost going to lay her first egg and ready for it.

 

[FarmShenanigans]

She is probably almost going to lay her first egg and ready for it.

so actually I found this egg on the floor today never seen any of my other chickens so I’m thinking it was hers. Only thing is that it’s kinda big looking for such a small chicken LOL