I think that the Extension Office could give you the best guidance on this question.

I say: go ahead a collect a bunch of samples, thaw, partially dry and mix well (assuming your garden soil is pretty uniform). Randomly select and package the amount of soil requested on the package or form and mail it in or drop off at the office.

Your test results will be different than if you had collected it in mid summer -- changing microbiology and thus nitrogen, for example.

I am going to agree with Marshall, if you are not concerned about nitrogen (which likely will be lost from a wet sample) go ahead and do it now.

Usually, in Michigan, there is a printed sheet that accompanies that kit and it would tell you that the sample you send in should be dry. You can collect soils samples now, but if your soil is frozen that will simply make much more work than you need to do. As anxious as you might be to have that soil test done, wait a while.
The labs at VSU or VTech most likely will not test for Nitrogen since the availability of N in soil is very soil temperature dependant, ie. how active your Soil Food Web is.

Thanks for all your comments. The reason I asked this question is because I'm a little concerned about how long I may have to wait until the soil is dry enough to sample versus enough lead time to make any adjustments necessary.

I know the lab doesn't want wet soil, which is why I asked about taking the sample and letting it "air dry" in the garage, for example, and would this skew the results.

Sounds like I might should wait, just to be safe.

Thanks again for all your opinions!

If you don't mind spending the money have a test done now so you'll have a good idea what adjustments you need then do another mid spring or when conditions are more favorable.