How long did it take your young toddlers to share a room without playing?

We moved our 2 y/o girl and 3 y/o boy into the same room to make room for our 7 months old and an upcoming baby. It's been 2 weeks now and still takes the kids 1.5-2+ hours to get to sleep during nap time. I've tried every approach, except bribery-because that's never a good idea; spanking, not spanking, nice, stern, leave them for an hour-then spank. I'm out of ideas. I thought surely by two weeks they would have it down. What did you do?