Don't worry about your schedules and just go for it!! Nobody's scoring you, it's just for fun!
I had a four month old when I started this challenge. I knew I wouldn't be able to keep up to one card a day, but the point was it provided incentive to me to keep going and to make time to craft.
At 100 days, I celebrated what I DID accomplish, and then kept going to get my 100 cards completed.
January 1st sounds like a great date to pick. Just go with it and see what happens!!