I think the solo group may meet at 5 on the first day of the cruise just to get a feeling for the size of the group and how many want to dine together during the cruise. I didn’t go to that 1st meeting because I assumed it was a singles meet-up type of thing. Silly of me. But the dedicated solo concierge goes to that event too to know how many want to to dine together and how many will be going to the show that evening, when there is one.
They meet that first time in the late afternoon at a public lounge, to meet other solo cruisers who, for various reasons, are not staying in a studio cabin. Not all solos choose the studio cabins. Some people don’t want to be in an inside cabin and have booked other cabin categories, but they still don’t want to eat alone at night.
I was in the solo occupancy studios for the first time and didn’t have the inside scoop. Thankfully, when the solo bar opened at 5, the bartender told me I should check it out at least once. I did and I continued to do it every night.
As to the specialty restaurants, there is no reason to feel awkward there. People in our group were often absent from the main dining room because they were at a specialty restaurant with other members of the group so that they could take full advantage of the specialty dining vouchers.
I seem to recall that we would meet at 6 or 6:30 for drinks and then head off to dinner around 7.
You should give it a try. I think it would have given you a more enjoyable specialty dining experience.