When we started putting DS to bed at a set time, it only took a couple of nights before he got used to it.
When he went into his single bed at around 19 months.... he would continually get up, and did so for a few weeks.
We put a baby gate on the door, and he's had no problem ever since. He happily sleeps all night once he goes to bed at 7.30.

Hope your little man sleeps well for you and adapts to his new routine super quickly!