My kids are 5 1/2 and almost 3 (June). They used to share a room, and the littler one would, for awhile, go to bed 1/2 to one hour before the older one. The older one learned to be super quiet when going to bed. Both kids now go to bed between 8-8:30 depending on the night. My almost three year old still naps most days, my 5 1/2 year old only rarely does. They get up at 6:45 week days and whenever they wake on they weekends, usually between 7-8. It seems to me no matter how early/late I put them to bed, they get up around the same time.
When we had them in the same room with staggered bed times, we would get the pjs out of the room and do the whole routine with the older kid outside the room, we also waited about 1/2 hour before putting the older one to bed so the littler one would be asleep before we put the older one to bed. Good luck to you. Sleep issues are the worst!