You may sign the log at any time, but you may not claim a find until you have met the requirements for the challenge as verified using the Challenge Checker.
The challenge is to find at least 5 caches in each of Santa Clara, Santa Cruz, and Santa Barbara counties. These are the three California counties with "Santa" in their name.
As required, I qualify for this challenge.
Though not allowed under new challenge rules, you can optionally note in your log that you have met these two other possible SANTA challenges:
State SANTA: Spell SANTA using the first letter of 5 US states starting with the letters S, A, N, T A
My qualifiers are: South Carolina, Alaska, New Mexico, Tennessee, Alabama
World SANTA: : Spell SANTA using the first letter of 5 countries starting with the letters S, A, N, T A
My qualifiers are: Spain, Andorra, New Zealand, Turkey, Australia