every dog is different. There's no set schedule. Sometimes they can be trusted from a young age and never have any problems. Some can never be left uncrated. My female is 3 and rarely is allowed left out uncrated. When she is, I gate off the kitchen and stairs so she's limited to the hallway, living room and keeping an eye on the doors. She's only been out for an hour and a half at the longest.
my dog was out of the crate at 4 months old. everything was
fine from 4 months to 8 months old. then at 8 months old my
dog decided he wanted to eat the house and everything in it.
form 8 months old to a year old or 1.5 yrs old he was crated
only when we weren't home.
start slow. leave your dog out of the crate for 5 minutes
and leave the house. 5 minutes becomes 15 minutes and 15
minutes becomes 30 minutes and so on. this is also a good
time to teach your dog not to counter surf. while i was teaching
my dog not to counter surf i would leave something available,
on the edge of the counter, edge of the table, the seat of the
chair, on the floor, etc. teaching him not to counter surf was
a seperate exercise but i use to include it in being not being crated.