Tips for getting youngest in bed when 3 dc share a room

[uhoh2016]

Just that really. Ds3 is 20m and in with us at the moment. We only have 2 bedrooms (although both big doubles) we plan to put all 3 boys together in the bigger of the 2 rooms. The older 2 are 9 and 6.
How do you manage to get youngest in bed early without the older children waking him or even preventing him going to sleep?

Used to have my 3 girls in one room ...best for us was staggered bed times so youngest went first and older one went in once they were asleep and then repeat. All in pjs, teeth brushed etc, story downstairs for older ones and def prepaying for sleep so they were calm enough to be popped straight into bed.

Staggered bedtimes with last trip to the loo and teeth cleaning all happening downstairs, once youngest is in bed then it's quite/settling down time, anyone who goes upstairs is quiet. The idea is that once the next one goes to bed the one who went before is asleep. I have also put blackout curtains around the lower bunk bed so that DC2 can read in bed without disturbing the others (he has light in there too).

I find the morning more of a challenge, DC3 will lie in if he is not woken but DC2 and 4 are early birds, I have to squirrel them both out and down the stairs before they wake anyone.