Micro worm composting

I only have about 4-5 worms that I have put in a small 500ml tub, with holes in the top and bottom.
I have added some chopped up cardboard, coffee grounds and some compost.

Will this work on such a small scale?

I am slowly adding more worms as I find them in the garden.

Any advice would be greatly appreciated.

Welcome to permies Mark
Compost and eathworms are different species.
If you found them in the garden you've most probably got earthworms, which need the relatively low organic matter in soil to live.
Composting worms are very 'active'. If they jump about, you've probably got the right species.
If they're slow-moving, it's probably earthworms.
Know anyone with a compost heap? They're usually a good source of compost worms.
Oh, but it's wintery over your way. Maybe not

I've decided just to buy some worms and make a standard size worm bin.

Thanks for all your help and advice.

Actually, this is an interesting idea. Just because the worms were gotten from the garden doesn't mean that they can't be red (composting) worms. If they're tan/gray, they're not, but if they're red or even just pink, and about 3 inches long, they probably are, and you could start a worm bin this way. I've heard of some simply sprinkling handfuls of corn meal in a damp area and coming back a few days later to find red worms milling around the corn meal (a red worm favorite).

Personally, I started my worm bin with only 200 worms that I got from the pet store. I applied a little patience with the food scraps, and after a while, I had a bin full of worms. Now, I have 3 smaller bins and one large bin. Yes, I bought those worms and knew that they were specifically the right species, but it's not that hard to identify a red worm.