I don't have official epilepsy but I have had seizures over 10 years ago.

My recommendation would be to make sure you have your Medic Alert bracelet at the very least.

Depending on your seizures, do you know when you are about to have one? If you can tell when your body is about to have a seizure, that would give you some time to alert the person next to you or the flight attendant and wouldn't require telling anyone in advance.

If your seizures occur with no warning, then it depends on how frequent you have seizures. This is what I would do: If you have been seizure free for several months, then I wouldn't alert the crew but just be sure to have your Medic Alert bracelet. If you have seizures more frequently, like more than once a month, then I would notify either the flight attendant or the person next to you depending on which one you might feel more comfortable telling.