score:2
Book it when you get there. Most cooking classes - even the popular ones near Bangkok's Khao San Road - are never full. Just book them a day before you plan to attend, although sometimes you can also walk in on the day itself.
Source: I didn't attend a class, but I looked around and spoke to cooking class place owners and people who took them at my hostel. I ultimately decided not to because I found them a tad expensive for my budget.
Upvote:1
Almost everything in Thailand is best booking here. Most things are over copied here, so it is rare there are over subscriptions (hotels, events or courses). They also take advantage of tourist willing to pay more via the internet and also often pay intermediary companies to host the internet pages and take a finders fee from it. Also, often the better ones (of almost everything) do not advertise on the internet (in English at least) and are easy found here (Thailand) but non-existent online.