The results vary and are hard to predict. Completely eliminating the portwine stain is rare, and very rare for a PWS that large. But even if it cannot completely disappear, it will be less noticeable and easier to camouflage with makeup if she wants. The technology is also still evolving, and every new generation of laser gives better results.
Yes, the treatments are cumulative, basically they are eliminating excess capillary vessels layer by layer.
The laser works a bit better the younger you are, and since there's less skin surface the younger you are, there's also basically just less skin to treat.
We mostly decided to start early because it will take a while (probably at least 2 years) to do all the treatments, and the effect directly after the treatment is actually (a lot) worse than the portwine stain itself, so if you start doing it "when it starts to be important to her", it's probably going to make things worse instead of better. So we would like to have (most of) the treatments done before she reaches an age when bullying etc starts.
Also, these treatments never do irreversible damage, so it's not the case that if we would wait for better laser technology, the results would be better than if we use current technology. We would probably get better results (and faster results) with newer technology, but we can still do the treatment now and then still do the better treatment later, if and when it becomes available.
It's mostly permanent, but not completely. Portwine stains do tend to become darker over time, so whatever residual portwine stain is left after the treatments, even if it is (almost) invisible now, it will probably eventually become visible. Some doctors recommend regular "maintenance" treatments to avoid re-darkening, others recommend to let it slowly get darker and do a new (series of) treatment(s) if and when it starts to bother the patient.
We're quite pleased with the results, but it's not a trivial thing: since the laser is quite painful, they do it under general anesthesia for patients younger than 15 years or so (for old enough patients they can use some form of local anesthesia and ask them to sit still even though it hurts, but for young kids that does not work). So it's not an easy decision -- it still breaks my heart a bit every time they put the little sleep gas mask over Lola's mouth and nose, and the crying (she doesn't like all those strange hospital people) slowly fades away as she loses consciousness. But I hope and I think we're doing her a favor in the long run. And we're now also using the opportunity of the regular anesthesia to get her eye checked regularly, which can be done much better under anesthesia. They can try to measure the eye ball pressure when she's awake, but it's a very tricky thing: you can't ask a 1.5 year old to sit still and keep her eyes open while they hold a measuring device against it, and if she cries and becomes angry, the measurement falsely reports elevated pressure. So the ophthalmologists want to put her to sleep anyway every couple of months to check the eye, so now we combine it with the laser treatments to keep the total amount of anesthesia low (after all, there's always a risk involved).
Nothing or nobody can prepare anyone for all the things that can happen in life. You can only try to make the best out of it, prepare for the bad things you should realistically expect, and hope for the best things you can reasonably expect.
