If you want your child to go to bed at the same time, in the same way, every night you need to create a structure that helps your child to understand that it is bed-time and that this is not negotiable.
The routine may differ in every family but whatever you choose make sure that it is one of diminishing activity: play-time, bath-time, story-time, sleep-time works perfectly. Story-time, bath-time, play-time, sleep-time is a recipe for conflict!
Engage your child in this routine
Talk about the routine with your child, such as asking him what book you are going to read together after the bath tonight before he goes to sleep. In this way he will start to predict the routine for himself and in time will engage in it happily.
It may take time for your child to accept that at the end of the routine it is time to go to sleep and, in the early days, you may have to be patient enough to return your child to his bed many times.
Be consistent and firm in your expectation that it is now time to go to sleep and he will start to accept it.
The routine may take time to establish so don’t give up the first time that it doesn’t work and allow your child downstairs until he falls asleep on the sofa. Although this sometimes feels like the easiest option at that moment it will only prolong the process of settling into a regular pattern.