Hi In modern times you can suit yourself and remove your hat before or after dinner. I think you should see what you feel like on the day; for example if you are realy hot and uncomfortable then please dont sit and suffer. Generally the other ladies will be guided by you but please dont be offended if anyone does remove their hat before you. Some people feel more comfortable to sit and relax at dinner and therefore remove their hat before hand; some people will sit with their hat on until you remove yours; and like your original thought some people will hold on until they can get to a mirror to fix their hair. In modern times we find that most ladies do what suits them. I hope this is helpful to you Have a lovely day MRS S