OS cues are hard to come by unless they're actually crying from it - my best advice is to stop just about ANY activity about 10-15 mins before you start your wind-down. From your list, especially video, exersaucer, jumper, walker.
Maybe all three of you could spend a little time lying/sitting on mummy and daddy's bed, just smiling and 'chatting', or looking at a book, for a few mins before the wind-down even begins.