I do, and I still have it It was Matchbox PK-12 F-5A Freedom Fighter that my father mostly built for me (as I was seven, I think, at the time).
This was followed by PK-24 Brewster Buffalo that I built myself, probably with a little help.
We put the decals onto the bare plastic (Matchbox's being the only ones I've ever seen that will reliably stick to that) and I painted both some years later, since I only got paint and brushes after my first couple of models.
If memory serves me well, this is one I've always claimed was my first. Probably got it for Christmas or my 9th birthday. I remember it sitting on my dresser for a long time, so building it must have went well.