Housework heroes - the best hoovers????

To answer your question - decades ago I believe. I don't think my mother ever had an actual Hoover, but she called all her vacuum cleaners hoovers. And she always did 'the hoovering'.

It's not in the least unusual for a brand name to become generic. There must be dozens, but I can think of:

Sellotape
Velcro
Thermos
Elastoplast

I would not say I Sellotaped something. I would say I taped something.
I don't think you can Velcro anything BUT Velcro. Not sure on that one.
The Thermos flask is not used as a verb. I've never heard of anyone Thermosing.
Elastoplast? Can't think of the last time I heard anyone call it that.

Yes, my mum did the hoovering too. The expression annoyed me even then. I was doomed to be a pedant. I hate it. We always fixate on something and its impact on our minds grows and grows...

I don't think you can Velcro anything BUT Velcro. Not sure on that one.
I have a metre of hook and loop tape in my sewing room that isn't made by Velcro.

The Thermos flask is not used as a verb. I've never heard of anyone Thermosing.
can't find where I said it was used as a verb.

Most people I know refer to sticky tape as sellotape. Elastoplast may have faded from use in recent years in favour of plaster, but it was most definitely used as a generic term for the brand name, whether or not it was made by Elastoplast.

Do you write with a biro? Brand name for a pen invented by László József Bíró, who patented the invention in Paris in 1938, and again in 1943 in the the USA as US Patent 2,390,636.

I actually would say that my hoover is a Dyson even though I know it's incorrect. I'd never say my vacuum cleaner is a Dyson and I would say that I'd sellotaped my parcel. I also wear Wellington boots (rubber boots made to joules probably) and I wear a mac ( made by Boden )

Who doesn't say 'wellies' and 'biro'? As for calling all cars Fords, I've never heard of that one.