Getting to the airport on the 1st day of CNY

I’ll be flying out of Taiwan on the 21st of January - the first day of Chinese New Year - and I expect busses to be full and the roads even fuller. I’ll be bussing from Taichung. Any suggestions as to how I can be assured of a seat on a bus that’ll get there on time? I’ve tried booking tickets in the past and had no luck. I will of course leave early enough to allow for an extended journey.

Sweet…