I just started my lo on solids (rice cereal only for now) about a week ago, and the first couple days we tried dinnertime, around 6:00pm. That did NOT work, he screamed the whole time and wanted nothing to do with it. The next day I tried at noon, and it was a huge success! I then tried again at dinnertime and the same result. I think that's just too late in the day and he's too tired for it in the evening right now.
So what I'm getting at is that I don't think there's a right or wrong time per say, you just need to find the time that your lo is alert and happy and interested in it - whatever works!