What age do kids shower themselves ?

My 5 1/2 year old has been telling me he wants to shower himself. I normally let all my kids do it alone and then I go in and wash them myself because I’m sure they don’t do it correctly. My oldest has been pretty much begging me to stop showering him but I feel like he’s too small 🥺 I also want to respect him because he’s very shy when my husband or I shower him. What age do kids normally shower by themselves?