Sleep

So I’ve made the terrible mistake of continuing on for the past year of cuddling my little boy until he falls asleep then putting him in his cot afterwards. I’m due to have my little girl in a little less than 4 months and I want to start getting into the routine of him falling asleep in his cot with his bottle of milk at bed time.. I honestly have no idea where to start or how to do this. Does anyone have any tips or advice? I’d be extremely grateful