Honestly, lying down for 15 minutes is more than enough, no need to do circus poses! I am in my 3rd trimester now and just turning around in bed is a task, haha.
I used to lie down for an hour without moving because I was so anxious! But actually, 15 minutes is clinically enough, so don't stress your body like I did.
My doctor at the hospital told me that sperm reaches the destination within minutes anyway. Lying down for 10-15 minutes is just for peace of mind, no extra medical benefit.