my missus says 8 if they are sensible

i see 3 year olds in the scummy arears round here, usuall accompanied but an older sibling but not always
shocking

i dunno myself, we live in the sticks bigtime, nothing but our 4 cottages for a mile, my 5 year old isnt allowed in past the sidegate into the front garden, she wont be going off alone for many a year