When I saw the first 1000 out of commodore corby. When the first 500 was available. Whenever that was.
My first play with any computer was a Nascom-1 and a Commodore Pet 2001 in May 1978, (HB computers ltd, Kettering were trying to demo their wares to the school), fortunately my friends brother owned the company so I got to see quite a few toys over the next year, one of the first VIC20's too. By 79 I was coding on the school Pet...

I'm old now

My own first computer took a few more years and I bought a Oric Atmos in 84 then a Commodore 64 (Got a broken vic20 case + a 64 board from the Commodore Corby, black market) in quick sucession, folllowed by a A500 in I think in 88 when I started work, by that time I was programming PCs and Dec Vax's.