If it is your first time at Food & Wine I would probably hold off unless you see something that really calls to you (for example, if you've always loved Robert Irvine or something). We have filled plenty of time each year just visiting the booths and the Festival Center. There are so many options just at the booths that we never get to try everything that we want to. If you follow this thread closely it can help get you excited about Food & Wine but for me it also creates a fear of missing out on events that otherwise there is NO WAY I'd be signing up for this far in advance or paying the premium prices on. We did a culinary demonstration once, back when you got wine included and it was $15. It was only a "meh" value proposition to me then, the portions were small of both the food taste and the wine taste, and they have since removed the wine pour and raised the price. I am not trying to rain on anyone's parade - if you enjoy the beverage or culinary demonstrations I am not saying you shouldn't! But you can also find availability on the day-of for many of those events, as others have pointed out.
In past years, you could also "lurk" outside the demonstrations for free and hear some of the content of the presentation (no tastes though). If the setup is the same this year, you might consider doing a little lurking early in your trip to decide if you want to schedule a demonstration later in the trip.
Also if you have ADRs I wouldn't overschedule F&W special events. You'll end up so stuffed you won't be able to experience anything at the booths, which would be awful for the way we like to experience F&W. Just my two cents but hopefully there's a helpful nugget in there somewhere