Its impossible to have a "proper" timing when it comes with ctb. There's always going to be tears and grief, yet christmas seems to be a symbol of merry relaxation and an abandoning of daily troubles for a at least a little bit. If you commit to leaving before x-mas, then they're going to be horrible for your close ones. Ctb after might ruin the image of christmas for them forever, since they were unaware of your plans and everything only "seemed" ok. Of course, I don't know your entire story and what it entails, but we're all human. Death always leaves its mark.
Ctb is ctb regardless of when it happens, anyway. When one decides to accelerate the instance of their death, then thoughts of empathy and concern are a good sign. You don't want people to suffer as you've suffered and death will forever remain a touchy...subject...thing...yeah...
When we're dead, there's a really good probability that the circumstances and the timing of our death are not going to matter at all to us. It's an escape from a burning building straight into the void, or at least this is how I see it, excuse me if it got edgy.
I've made my decision. I'm trying get my ticket right now.
Whatever your decision turns out to be, I hope you're making it as informed and thought-out as it can be. Life isn't easy but so is leaving it. I wish you best of luck, no matter what happens.