Wee little bow set up

[bisblue]

Hey folks I was gifted this kids bow when we bought our house. Measures about 50.75" and I had a 48" string made. How do I go about figuring out a good brace height for this bad boy? Currently it's sitting at 5 3/4".

My son who is 5 will be shooting mismatched broken arrows, but his age bracket can get fairly competitive.

 

[oldgoat]

Twist it till you can see an 1/8" to 1/4" of the string grooves