Need some advice on what to say to stop her walking with me?

I have two dogs, one is a puppy and i am currently in the process in the training her. There is a woman across the road with a dog and she likes to come out and walk her dog with me and mine as she thinks it's good for her dog to have some playmates. I don't mind walking with this woman but it's becoming too much, if i haven't passed her house by a certain time she will sometimes knock on to see if i am coming out to walk, but i am trying to train my puppy doing things such as sitting at roads and telling her 'wait' and 'ok to go' etc. The woman is saying when it's okay to go etc etc though and i want the dogs to listen to ME not her, also, i don't want to walk with the woman EVERY day! I don't know what to do or say to hint that sometimes i want to walk them by myself, any advice?