On my (much better developed) girls’ list, there’s a clear pattern. A leads by a long shot, followed by C, M and S. Obviously, there is some effect from what are common first letters for names in the first place, but the exceptions are also notable. J and K are common for names, but there are few on my list.
The situation changes somewhat when I consider which names I’d actually use. The list is already biased toward uncommon names. Trying as an exercise to see what names I’d use on a large number of children, eliminating common names and names that sounded too similar, the results changed. S was now the commonest first letter.
The male list is different. C leads, and some letters absent or nearly so from the girls (H and W) become common. Again, that exercise led to an expected result (less C’s, because many of those are too common) and a surprising one (the number of V names in consideration).