I have a DD who is 8 months and my friend has a DD who has just turned 4 months.
We have both been invited to another friends house (who has 2 dc, toddler and school age) with our DC's for food, early evening.
My friend doesn't want to go as her DD goes to bed at a certain time and she doesn't want to alter this.
AIBU by thinking that it doesn't harm children to have an occasional change to their routine.
My DD is usually in bed for 7.30 but if we are out somewhere and it is later, then I don't worry about it. I did this with my older DS and he was a brilliant sleeper and still is at 7.