How to book Zao Snow monsters Snowcat Night Tour?

Hi, as the title says.

I'm heading to Zao for a few nights in mid-late January for some skiing, and hoping to do the Snowcat tour at night time but struggling to find where or how to book it, or if its just a case of rocking up on the night? Hoping someone who has done it before (or someone with better google-fu than me) could point me in the right direction <3

cheers!