To expect friends to show up for dinner on time

[Sprite21]

DP invited friends for dinner tonight and told them 6pm, then earlier today asked if they could make it any earlier.

They texted at quarter to and said they would arrive for 6:40, with no other explanation. We timed everything for 6 so now it's all sitting there getting cold.
I know 6 is early for dinner but we have to eat then so we can eat with DD, 18 mo and then get her into bed.
So AIBU?

It is rude to complain to your host about them for anything. The polite way is to say," We'd love to baby sit DD. We are so looking forward to it, when you need us". They sound too pushy for my liking.