Sat and Sun, there's a normal Southern service. So there's 4 trains per hour to London Bridge for changing onto the Jubilee line.

Mon and Tues, the Overground terminates at Shadwell. So travel to Canada Water is good.

BTW - the recent tube strike made it clear the Overground is popular because of the convenient interchange at Canada Water. On that day, the carriages were 90% empty. Everyone must have piled onto the Southern trains for London Bridge.