I get why we tend to make "resolutions" at the start of each New Year, but I'm starting to think it's the worst time to actually make lasting changes in your life. To whit: I had a simple New Year's goal of simply going back to kundalini yoga classes on a regluar basis, and doing a hot yoga class once a week. We're two weeks into January and I've already failed. Why? Because when I got back from my holiday trip, I got sick (not surprising with all the stress - and germs! - of traveling). I've also been swamped trying to catch up on work that did not get completed prior to Christmas.
The beginning of January is a stressful time that often ends up being just as busy as the holiday period prior to it. Maybe it would be better to start a new yoga practice during another time of year? Maybe all New Year's Resolutions should simply be set in another month entirely! We could pick a month that doesn't have much going on otherwise. A month where no-one is stressing about things like Christmas presents, Valentine's gifts, or Halloween outfits.
In scanning through the months of the year, my suggestion would be either March, April, or May. This is because spring is a time of renewal, and the holiday stress is pretty light. No-one really stresses out about St. Patrick's Day, Easter, or Cinco de Mayo.
My birthday happens to be on March 31, which is the end of the first fiscal quarter as well, so for me I have a double reason for starting a "New Year's Resolution" on that day.
Another good day might be the "Ides of March" - March 15. Technically a day of "omen" but it could be repurposed, and it's at least memorable.
For Christians who do yoga, Easter would be an excellent time to start. It's in the spring, and is a day celebrating rebirth. It doesn't fall on the same Sunday each year, but that's OK.
May Day - May 1st - is also a contender, if you don't mind that it is also celebrated by Marxist communists worldwide as "International Workers' Day."
Ultimately, it's up to you when you want to commit to a new yoga practice. I think it's great to mark it with some sort of special day each year. But don't wait for New Year's or your own special "Yoga Day" to commit or recommit to yoga. Each day can be a new day of commitment.