Ceremony and reception timeline!

Long post, I will try to explain everything very well so you don’t get confused (usually, I confuse people a lot for my poor English), my ceremony will begin at 5:20 and end at 5:40 (it will only take 20 minutes or 30 minutes) my reception begins at 6 after the ceremony and will be in the same venue but different room. (I will take some photos with my guests until 6 o'clock arrives.) HERE COME WHAT CONCERN ME. I want to make a great entrance just before dinner, which would be at 7:00 because I want to give dinner when most of the guests have arrived (because people are always late), but what would the guests that are already at the reception doing? they would be without my fiance and I for an hour, of course, in the meantime, I will give snacks, juices or some dessert. (It will be a non-alcoholic wedding) but I still think an hour is too long. and I don't want to have dinner at 6:00 - 6:30 because I know that most of the guests haven't arrived. My mother suggested to put in the invitation that the wedding will be at 4:40 without saying the reception time so that all the guests are there at 6 in the afternoon and have dinner at that time so that way they won’t be alone for an hour. But I don't know if it's a good idea. A need advise