You could maybe use a treat to help, our routine at the moment - I get mine to sit before I put there collar & leads on they then get a biscuit each. We go out the door and again I get them to sit and get a biscuit, we then start our walk, any messing from either we all stop - they sit and look at me like 'what?' then were off again.
The Dogs Trust & youtube have some good videos on getting ready & going on walks, pulling etc.