What would be the correct time to let my 8 month old labrador roam freely inside my house?

i have an 8 month old male labrador. he is very naughty. we generally keep him tied up coz if we alllow him inside our house he destructs just everything. but i want him to roam free inside our house. he is very active and energitic. this makes me afraid to bring him inside.and some times he even poops where we dont want to. i am also having trouble in potty training him. what to do....?