With the exception of braggots, I never send in anything under a year old. Most of my entries are 1.5-2 years old. Essentially I let them declare themselves before sending them in.
The decision to send entries is one you have to weigh. All of us can have bias in our tasting, and we can get used to aromas and flavors that others don't happen to enjoy; sort of like folks who work in the hospital don't notice "hospital smell" when they walk in the door, and that may be the first thing that hits you. Sending samples that get professional tasting for $6 is a great bargain that can give you some unbiased insight which can help refine your recipes and technique.
But you can't be thin skinned. Sometimes other folks just won't like your meads, and even though they offer their comments with professionalism and respect, it can hurt. No one wants to hear their child is an ugly-duckling, and when you receive negative feedback about a mead that you've put heart and soul into, it really stings. But if you can get past that and use the insight you receive, it can be invaluable.
If you can go in person, I'm sure it's even better.
