I'm not sure many are putting out their vegetables and annuals that early - some maybe, a sow and forget them to have them done and out of the way...

But many times annuals and vegetables are the last things sown, they aren't going to germinate until weather begins to warm a bit.

Many perennials, trees, shrubs will need 90 days or more of chill - those go out first for me, Solstice may even be late for a few of those seeds.. marking the Solstice by way of sowing a few things is a way of recognizing the season. However, I don't anticipate having much free time that week and likely will be sowing nothing. DH is already making noises like he'd enjoy digging clams that night! As though Christmas and all the food prep etc just takes care of itself magically ;), and sandy wet clothes and sandy clams in the shell are no extra chore at all.

I start on the solstice with trees, shrubs and any perennials that require a lengthy cold moist stratification period. Once those are WS and set outside in Dec., Jan. & Feb. I move on to the perennials that don't need cold strat. I'm hoping to keep the container count under 200 this year but have already collected and/or traded for 67 mostly new-to-me seed types. After two years of WS, there are quite a few things I don't need more of so I can scratch those off my WS To Do list this time around.

What kind of shrubs you can WS? don't they take long to grow?

Some shrubs grow slowly, others at a rate taking less patience. Many can be wintersown -

Browse through here for ideas - those suggestions that say moist chill will work, those that indicate they do better with a warm period first are better sown in Fall and left outdoors over winter.

Here is a link that might be useful: Clothiers tree/shrub database

So far I've grown spirea, St. John's wort, blue mist shrub, potentilla/cinquefoil from traded/harvested seeds either from my own or the neighbors' shrubs. The spirea & St. John's wort grew 8-10" tall the first year after WS. I also WS apple, pear, & two types of dogwood tree seeds. Germination rates on all were 100%. The dogwood trees grew 12-15 inches the first year and that much again the second year.

This year I traded for Japanese red maple, threadleaf Japanese red maple & received both Japanese maple 'Emperor 1' & Tatarian maple seeds, along with beautybush & golden rain tree seeds from a generous WSer. I lost nearly a dozen trees in the October snowstorm and many more were severely damaged. Might as well get started growing their replacements.

I sow on winter solstice to be part of the winter solstice celebration of wintersown.org.

The only other seeds that get sown that early are ones that take 2 cycles to germinate.

Here is a link that might be useful: Solstice Celebration

I've sown my purple beautyberry bush, Sycamore tree, and acorns already, about three weeks ago. I have about 130 jugs collected but haven't gotten any of them prepared and feel like I'm already behind.

You are not behind. Heck, you've got all winter to prepare and sow your jugs and winter hasn't even started.. Most seeds don't need cold stratification and can be sown later, ie spring, if needed. Concentrate on getting those that do need cold strat done first. Next perrenials, then hardy annuals, tender perrenials and tender annuals.