I’ve noticed my visa (did I mention I’ve got a visa? 
) is valid from a date two days after I am due to arrive. I put the correct date but they have used Madame’s date.
We are nowhere near the 90 days. It’s VLSTS inactif.
It won’t be a problem, will it?
Sounds like you have two days of being a tourist! 
As long as they don’t make you catch the ferry back again and re-arrive two days later…
aren’t you old enough to travel on your own… 
perhaps the issuing authority think Madame should be supervising you.
EDIT:
Might be an idea NOT to flaunt your Visa when coming over this time… someone might notice that you are “tooo early”… and refuse you … aaaargh.
I will be travelling with the cat … but no, not really responsible enough to be left on my own …
I shall exercise caution and discretion
Just get the cat to sweet talk the police aux frontières 
I believe that when you validate your visa, which you have to do online shortly after your arrival, you have to enter your date of arrival which is normally the date stamped in your passport. Obviously you cannot enter a date of arrival that is before the start date of your visa. Whether it would matter at all that the date of arrval that you give is not the date when you actually arrived, as stamped in your passport, I do not know.
Just an update, having heard from the consulate.
To be legal, I would have to enter no sooner than the “valid from” date.
I could enter before the visa, but I’d then have to leave the Schengen area and return on or after the visa date.
Or I could travel to London in the meantime, and they could edit it, which is unfortunately not possible.
(At no point was there the ghost of an apology )
sounds like you’ll need to delay your Entry to France… if you can’t get to London…
For me it’s a no-brainer…
knowing full well that (with my luck) if I entered France before the date on my Visa… I’d have some sort of “happening” and the Insurance/whatever would be negated as I was here illegally…
aaaargh.
You’re right, @Stella . I’d rather not blot my copybook on arrival!